I've created a few applications that have been targetted against 2.2
I'm thinking to invest in a cheap handset to try these out (thus far only used emulator). The handset I want is running verion 2.1 of Android.
From a code point of a view, is there any major changes between 2.1 and 2.2 that could potentially cause me an issue?
I understand there would be issues if I was trying to deploy to a 1.x handset (such as People/ContractsContact etc) but I can't see anything to say a 2.2 app would fail on a 2.1 environment
(I could try to change emulator target, but curious to know from others with actual handsets)
Here's the page that might be useful to you: http://developer.android.com/sdk/api_diff/8/changes.html
You can cross-check all your packages and methods used to the differences list.
Like Juhani said, if your app uses any of the new APIs, then that would mean a high possibility of your encountering problems.