Having a project in my school investigating how smartphones can be used in teaching-learning process. We bought three Motorola Milestone Droid (android 2.0) and tested apps and using them in education.
So far we found lots of APPs that are exellent: Scan2PDF, gTask, FoxNote, Mobisle Notes, Seesmic, GoogleBuzz, 3banana, Gdocs, Aldiko, ActionComplete, wpToGo, PDFView, OffiView,Droidbox (dropbox)Meebo IM and Dolphine Browser just to mention a couple...
We encountered problem with our surfzone however and but are fixing it.
Another discovery was that the students was quite poorly oriented in the capacity of their phones and the most basic programs like calender and to-do lists. Therefor we have to develope a strategy and tasks that help the students methodically explore and use these programs.