Did someone else noticed that yesterday around 8PM EST, all paid apps in top grossing charts jumped up about 50 spots while all F2P apps dropped down the same amount ? Nothing changes in regards to revenues per day but some of our apps experienced huge drops or gains in charts. You can check out the status here: http://appshopper.com/bestsellers/games/gros/?device=iphone&sort=change&dir=desc
We saw that with Block Fortress, but I think it was just a glitch... it didn't happen universally to all paid games (not even all the ones in the top), and it seems to have stabilized today.
Yeah something changed with the rankings all around - on purpose or otherwise... I had a couple games consistently ranked in subcategory top 300's (mostly in Europe) and as of today they're not ranked at all. It makes more sense now though, 'cause these games sell squat. The paid ranks only went up after relatively successful free promos, which I always thought was a bit strange.