If you want more maps like Snowblind for Gears of War 2, you'd better show your appreciation for it. The game's executive producer says that the specifics for the next DLC will depend on the reaction to the DLC.
Speaking at GDC, he said that:
The big focus is on Snowblind, which is out Tuesday, and we ll see how that s received, along with the title update. I ve been checking in on the forums late at night to see how people are responding at it seems to be pretty positive.
A new pack is rumored to come out this month, supposedly titled Dark Corners. We'll probably hear more about it in the next few days.