Adobe have announced that their upcoming Flash CS5 software will allow developers to export native Apple iPhone apps. It doesn’t look like it can’t use native iPhone UI widgets, so the vast majority of apps will probably be games.
MonoTouch would still be my choice of alternative iPhone developer platform. C# over ActionScript, .NET Framework over AIR APIs. Version 1.1 of MonoTouch has added support for interacting with SOAP web services, and Microsoft has even ported their XNA Framework for creating games to MonoTouch.