Adobe has released Flash Builder 4.5.1, a free update to Flash Builder 4.5. The big news is that it now targets Apple iOS as well as Google Android and BlackBerry Tablet OS (as used in the PlayBook).
Although Apple iOS support in Flash Builder was announced when Creative Suite 5.5 was released, it has only now been made available. I will be testing the new support shortly so check back soon. In my simple cross-platform test app, mobile AIR was one of the better performers on Android, so if performance is good on iOS as well this will prove a useful tool.