I just saw it available for download. Trying to download it now n see if it'll work on my ipad1. Can't say where I saw it available at but it's there n I'm trying to download it now ;-) it says requirements ipad2, iPhone 4 or 4th generation iPod touch. Also iOS 4.2.6 or higher. Ima still try to see if it'll work.
GarageBand also available, says it wrks on ipad iOS 4.2 or greater. Definitely know that'll work on ipad1 then. Fingers crossed on imovies though.