Personally I'm currently using GLBasic. Worked on a PC, and with a couple of iOS plugins (eg. accessing the iPod music and iAds) I recompiled for iOS and chucked the app on the app store (Rotaslider). Easy. Just got a Palm Pre and without any code changes it is exactly the same on a re-compile (obviously iOS specific APIs were ignored).
Worked perfectly on my Pre 2, with the exception that the touch screen seems slightly more sensitive than the iPhone so I'll have to change one parameter and that's it done. Android is in the next beta of the language, and with a bit of installation and a recompile (again no code changes) it works on my Android tablet too. Ok so it's a little slower on the tablet (compared to PC/iOS/WebOS), but it's the beta version of the language and looks to constantly run in debug mode, but so far so good. Oh, and plus I have a cheap Chinese import tablet so is of questionable quality...
Cheers
I am 99% probably lying in bed right now... so don't blame me for crappy typing
Current fave quote : "She was like a candle in the wind.... unreliable...."