Yes. Last example: Angry Birds It wasn't in the Market at first. And many seem to do it since getjar.com was down some hours after Rovio announced via twitter

Yes. Last example: Angry Birds It wasn't in the Market at first. And many seem to do it since getjar.com was down some hours after Rovio announced via twitter that you could get it there. I host pre-beta versions of my Apps on my own servers and give friends (and their friends) access to it. This would be impossible with iOS. I would have to know and register the hardware IDs of all devices in advance.