Can apps be compiled offline?

[FiftyOneFifty]

Forgive the newbie question. Much has been made of the JIT compiling in Froyo. I assume apps are not distributed in native language to avoid requiring a separate download for each device. For older phones and tablets that won't see Android 2x, what would be involved with obtaining a SDK and copying the APK to a desktop, compiling it, and copying the app back to the device in native format?