comScore released their December search engine rankings report, showing Google increasing share a little while Yahoo dropping share a little.
Google Sites led the U.S. explicit core search market in December with 65.9 percent market share (up 0.5 percentage points), followed by Microsoft Sites with 15.1 percent (up 0.1 percentage points) and Yahoo! Sites with 14.5 percent. Ask Network accounted for 2.9 percent of explicit core searches, followed by AOL, Inc. with 1.6 percent.
The folks at WebmasterWorld are expecting Microsoft Bing to increase search share at a much larger rate in 2012. I am not too sure.
Forum discussion at WebmasterWorld.