Rovio's wildly popular continuation of the Angry Birds franchise, Angry Birds Space, has taken over as the top grossing app in Apple's App Store. Early reports put it at over 10M downloads in the first 3 days. Angry Birds Space replaced OMGPOP's Draw Something, which has held the top spot for some time now. Both OMGPOP's Draw Something Free and paid version have a spot in the top grossing list.
Rovio has quite the money-making game series on their hands. This may explain why Zynga had approached them with a $2.25B offer prior to Zynga purchasing OMGPOP. OMGPOP must be excited that they held the top spot until after the deal with Zynga went through. Had they not, the offer might not have been so high.