According to the folks of /. (SlashDot), Google is preparing the launch of their own browser, Gbrowser. Evidence include the registration of the gbrowser.com (currently not in use) domain name by Google and the fact that they hired several developers recently.
According to evidence in Mozilla’s Bugzilla, the browser might be based on the Gecko rendering engine
Update:
More information can be found here:
More evidence of a Google browser
The Google Browser
Google picks Gates’ brains
Google Browser?
The Google Browser