So, is this "cheating," as Singhal specifically alleges? The experiment had to be run with Bing's toolbar and / or Suggested Search feature activated, which it explicitly says are used to collect data and improve services. And more popular search terms do return different results, It's not as if Microsoft is using non-public information, but is this an example of taking an unfair shortcut? That's a debate we imagine with rage for quite some time.
Update: Microsoft's been sending out the following statement from Stefan Weitz, director of Bing:
That's pretty ambiguous, so ZDNet's Mary Jo Foley pressed for a followup and was flatly told "We do not copy Google's results." We're sure there's going to be a lot more analysis and discussion to come -- this ought to be fun.We use multiple signals and approaches in ranking search results. The overarching goal is to do a better job determining the intent of the search so we can provide the most relevant answer to a given query. Opt-in programs like the toolbar help us with clickstream data, one of many input signals we and other search engines use to help rank sites.