Bing
Anil Dash has an essay up, Google's Microsoft Moment, (H/T, Charles Iliya Krempeaux) which will be roughly correct at some point in the future if not now. Organizations go through changes in a predictable manner, and Google is unlikely to defy the inevitable laws of corporate evolution. On a related note, Bing Delivers Credibility to Microsoft. Bing is OK, but I wonder how much of the relative openness to it is conditional upon the reality that Microsoft's star is in relative decline in the firmament of technology companies, and so there isn't a reflexive hostility engendered by genuine fear…
Two positive assessments of Bing. Google is my main search engine, but I use Bing's image search preferentially now since the UI seems less kludgey.