Here’s an update to the post about the iPhone Band.  Josh posted an update listing out the apps used (all links open iTunes):

Guitars: (Electric and Bass)
Pocket Guitar ($.99)

Piano #1:
Virtuoso Piano Lite (Free)

or
Virtuoso Piano

Piano #2:
Pianist ($3.99)

Drums:
DigiDrummer Lite (Free)

or
Digidrummer ($1.99)

A few other things to keep in mind:

1. If your students are using an iPhone have them put it on Airplane mode, so they can still get to apps without having to receive phone calls.
2. Also turn off all notifications in the settings app on itouches.
3. If you do the bit with the phone call, make sure the one person getting the phone call has their phone set to receive calls. Also, the person calling has to be in another room because the sound system will echo through the phone and the main house.

This should give you everything you need to do your iPhone band.