BBM has launched cross-platform today for iOS and Android and to no surprise it has been downloaded enough times to garner itself as the #1 Top Free App in the iOS App Store. All this happened within just a few hours of being released. What's even more impressive is that it has almost hit the 1,000 reviews mark for the day.
As for Android, it looks like we'll have to wait till their storefront propagates to the new numbers, but I'm betting it's a safe guess to say that it is in the top 5 no problem.
All you new, and existing, BBM users be sure to hit up our BBM forums for more info and to add some BBM friends.