And they did.
Bing grew its search share by 0.4% last month. That's a total of 2.7% gain since launch. Unfortunately, for Microsoft, the expense continues to be due in part to sinking search share at Yahoo! That means when the two merge their search efforts, Bing won't have gained at all.
However, if Bing can grow the combined search effort the way they've been able to grow since launch, they could be looking at some very good progress indeed.
Here are December's numbers with a look at November 2009 comScore rankings below that to compare.