Since the iPad 2 is used in therapy, I had some concerns about how to ensure that it stayed clean and germ-free. I purchased ZAGG foam, which is a gadget cleaning foam that is supposedly safe and made for iPads.; however, per Apple, they don't recommend anything other than a very slightly damp cloth. I have a screen protector on my iPad, so I feel fine about using the foam. So, if you don't have a screen protector, it's probably best to follow Apple's advice and use a fine cloth or a cloth that is just slightly damp.
The foam also has no CFC's and is antibacterial. It came with a small cloth. I bought a 2.7 oz container at Target for $9.99. I will post a review on it as I use it. They also sell a wipe style product, which I have not yet tried...but I thought I'd try this spray first to avoid having to throw out individual wipes. This is also the same manufacturer as the screen protector I bought, which is the ZAGG invisibleSHEILD. With as much use as my iPad 2 will get, I felt having the screen protector was necessary.
UPDATE (4/12/11): I think that next time I'd go with a different screen protector. It got highly scratched by a student during a therapy session...under careful supervision! This is the screen protector, not the foam. The foam continues to work nice and I would HIGHLY recommend the foam!
UPDATE (2/21/2012): I finally grew tired of the protective skin on the iPad, so I removed it. For now, I will just use a slightly damp cloth or dry microfiber cloth. As always, I try my best to watch the students to ensure that their hands are clean before using the iPad.