Back in October, Bing announced that it uses over 1,000 signals used to determine how to rank pages. Google has typically quoted using more than 200.
It took less than a month for Google to publicly "catch up" to Bing. Speaking at Pubcon, Matt Cutts, head of Google's spam fighting team said that Google has over 200 signals and many of them have more than 50 variations within a single factor.
Again, there's no accident here. Take 200 signals, multiply by 50, and you've got a claim to having 10,000 signals -- and a way to say you just didn't suddenly "up" the number but that there were always 10,000 factors. (Note: I dropped a zero in my math, originally saying this brought Google up to 1,000 signals, matching Bing. Instead, it's potentially shooting for a 10X figure).
So it wasn't like he had a big talking point about how Google's ranking factors outrank Bing's. And he said that he didn't want to get into a "numbers game" over the issue. But then again, he did toss out the figures.