As expected, iMovie and GarageBand are now available on the App Store for the iPad 2 when it releases later on this week. iMovie is actually just a universal update, since the app was already available for the iPhone, but it won't run on the original iPad (GarageBand will, however). Both apps are available for $4.99. Note that the GB download is pretty big -- GarageBand will run you 370 MB, so if your iPad is already pretty full, you'll have to delete some apps or media.
GarageBand offers up all of those great in-app instruments to record with, so if you have an iPad 1 or 2, it's probably a must-get. iMovie's improvements for iPhone users have yet to be tested, but it's bound to be a big hit tomorrow once the iPad 2 units hit the street.