According to a public announcement from Canonical's Rick Spencer, Ubuntu will be undergoing a slight change, beginning with the release of Lucid Lynx: https://lists.ubuntu.com/archives/ubuntu-devel/2010-January/030065.html
Firefox, which comes as the operating system's default browser, will now use Yahoo as its default search provider. However, this doesn't mean that Ubuntu users are stuck with it. Of course, a user can change it back to Google, or whatever else they desire.

The change was made after Canonical made a revenue sharing deal with Yahoo. This will bring in extra revenue to a company that prides itself on offering free software. Here's Rick's statement regarding the deal:

"I am pursuing this change because Canonical has negotiated a revenue sharing deal with Yahoo! and this revenue will help Canonical to provide developers and resources to continue the open development of Ubuntu and the Ubuntu Platform. This change will help provide these resources as well as continuing to respect our user's default search across Firefox."

So there you have it. For Ubuntu to continue its success as a free operating system, money is essential. This opportunity gives Canonical the ability to continue giving users what they want without having to worry about funding. It's seems like a small price for users to pay for their favorite flavor of Linux. If a user is savvy enough to run Linux in the first place, he or she won't have any problems switching their search engine back to something else. Ironically, since Yahoo will soon be powered by Bing, Microsoft, as someone at Slashdot pointed out, will essentially be paying users to use a non-Windows OS.

(Neowin)