I hear all this stuff about crazy ways to build iPhone apps using Ruby or C# under .NET or the like. Even stuff about developing apps on Windows using Java, or auto-generated apps using Flash CS5 or something.
Now, I've never really spent any time at all investigating these claims—I just brushed them off as clumsy or cumbersome or downright claptrap—but I'm a proud Objective-C programmer who's perhaps a little worried as to whether there's any truth in all of this?
As far as I'm aware, Apple is actively blocking apps developed with tools like you mention from appearing in the App store. That makes whether it is possible pretty much irrelevant.
I imagine that if this is possible it will soon be stamped out by Apple. They are very aggressive with their licensing terms.
As of the newest iPhone OS license agreement by Apple, all apps for the iPad, iPhone, iPod must be either built with XCode/ObjectiveC directly, or be built using HTML/CS/JS (With libraries like PhoneGap if desired). The Flash CS5 to iPhone cross compiler has been pretty much expressly forbidden. You can read about it from Steve Jobs.
I guess the only time those tools would be viable is in a corporate environment, where you were installing the apps directly on the phones.