Microsoft launched a comparative shopping feature in its Live Search engine on Wednesday. The service offers consumers a rebate on purchases made through the site, a scheme that could lure shoppers from Google and Yahoo.

The idea for Microsoft's " Live Search cashback" came from a Web site called Jellyfish.com, which Microsoft bought for an undisclosed amount last year.

Products found during a search eligible for a rebate are denoted with a gold coin icon with a U.S. dollar sign in the center. The rebate is based on a percentage of the purchase price and is determined by the advertiser.

For example, a search for a 4GB flash memory SD card from SanDisk showed a rebate of $2.12 offered by a retailer for a card priced at $52.99.

So far, the cashback option will only be available to U.S. citizens. Shoppers must set up a Microsoft cashback account, where the rebate money is held. When the amount reaches $5, Microsoft will either mail a check or transfer the money to a PayPal account or bank account. The rebate money is not released until 60 days after the purchase date in case the item is returned.

The cashback program offers an advantage for advertisers in that they only have to pay when they sell an item, known as a "pay-per-action" fee. It also avoids the problem of click fraud, where bogus clicks on an ad drive up marketing costs.

With the U.S. economy slowing, Microsoft's cashback program may be more appealing to advertisers with smaller budgets who only want to pay for completed transactions rather than for click-throughs from Google ads, said Mike Davis, senior analyst for Ovum in London.

"The Microsoft bit will potentially be more attractive to people with less money to spend," Davis said.

The cashback feature also thrusts Microsoft into an online retail market where it could potentially affect businesses such as eBay and Amazon.com, Davis said.

Persuading people to change search engines isn't easy, since people tend to stick with the one they're most comfortable with, said Alex Burmaster, an Internet analyst with Nielsen Online. For many people, that's been Google.

But it's a step in the right direction for Microsoft despite a consensus that Google will most likely dominate the search market for at least the next two years, Burmaster said.

"I think Microsoft should be applauded for doing this," Burmaster said.

The cashback site is one way Microsoft is trying to draw interest in its Live Search engine, which ranks a distant third place compared to Google and Yahoo.

Google was used 58.4 percent of the time by Web surfers in December 2007, according to data released by Comscore, which tracks the search engine market. Yahoo held a 22.9 percent share, with Microsoft at 9.8 percent.

Last week, Comscore said the number of visitors to Google's Web properties surpassed Yahoo for the first time in April, at 141 million. Yahoo's sites came in a close second with 140.6 million visitors with Microsoft's Web sites coming in third at 121.2 million visitors.

Microsoft's desire to boost of the popularity of its search engine also seems to be at the heart of its contentious discussions to acquire Yahoo. As of late, Microsoft is reportedly interested in buying assets related to Yahoo's search engine.

Red Hat is announcing availability Wednesday of Red Hat Enterprise Linux 5.2, with enhancements in virtualization, clustering, and hardware support.

Version 5.2 was described as a minor update by Red Hat's Daniel Riek, product marketing manager for Red Hat Enterprise Linux.

"We do these twice-a-year updates," Riek said.

With the release, virtualization of very large systems with as many as 64 CPUs and 512GB of memory is possible. Support for NUMA architectures is featured as well as improvements in security, performance, and management, Red Hat said.

CPU frequency scaling is offered for virtualized environments and for reduction of? power consumption. Also, enhanced capabilities are featured for such hardware architectures as Intel X/86/x86-64, Itanium, and IBM Power and System z. These capabilities provide for improved performance, power usage, scaling, and manageability, Red Hat said.

Support for Intel's Dynamic Acceleration Technology permits power saving by "quiescing" idle CPU cores, Red Hat said. With quiescing, a computer is put into an inactive state to save power but can be reactivated quickly because it is still available and has not been completely shut down.

Also, performance is improved by "overclocking" of busy cores within safe thermal levels. Other hardware enhancements include device driver updates and certification of IBM Cell Blade systems.

A smarter scripting facility boosts clustering in version 5.2, said Riek. "The ability to talk to the applications that are being clustered has been improved," he said.

Red Hat Enterprise Linux 5.2 Desktop, meanwhile, includes enhanced support for laptop suspend/hibernate and resume, updated graphics drivers, and an update of desktop applications including OpenOffice 2.3 and Firefox v3.

Red Hat Linux 5.2 is available Wednesday via a Red Hat Network subscription.

A group of experts has released an open-source alternative to the BIND DNS server software that boasts higher performance and better security.

The new DNS server -- dubbed Unbound 1.0 -- is available  here. 

Unbound is a recursive DNS server, which is used by ISPs and enterprises to support DNS look-ups by users. DNS is the feature of the Internet that matches domain names with IP addresses, and it is used for Web browsing, e-mail, and Internet-based telephony.

Unbound was released Tuesday to open-source developers by NLnet Labs, VeriSign, Nominet and Kirei. NLnet Labs, a nonprofit research firm based in The Netherlands, will provide ongoing support for the software.

From its first prototype in 2004, Unbound was designed to be a faster, more secure replacement for BIND. Unbound supports DNS security extensions ( DNSSEC ), which authenticate DNS lookups but are not yet widely deployed because they rely on a public key infrastructure.

"One of the main advantages is that it's high performing. We designed it from the beginning to be fast," says Matt Larson, director of DNS research with VeriSign. "We also designed it from the beginning to support DNSSEC. Other DNS servers had to bolt that on, but we were able to start fresh."

VeriSign has tested Unbound but isn't using it in production mode.

VeriSign runs the authoritative DNS servers for .com and .net, which are the servers that respond to queries from recursive DNS servers like Unbound. VeriSign uses homegrown software it calls ATLAS for its authoritative DNS servers.

VeriSign said that by offering Unbound to the open-source community, it is trying to give back to the Internet community.

"Our goal [with Unbound] is to have an active community. We want to get to the point where the community is looking at it, monitoring it and adding patches," Larson says. "This is just another example of VeriSign's innovation. We're always moving forward."

Developed in the early 1980s, BIND (Berkeley Internet Name Domain) is the most popular DNS server software on the Internet. However, BIND has suffered from serious security flaws, even in its current release, BIND 9.

BIND alternatives already exist, including DNS server software from Microsoft and Cisco and appliances from Infoblox, InfoWeapons and others. Another option is free DNS services from OpenDNS and NeuStar.