Syncing music onto your iPad and iPod and between the 2 really depends what iPod you have. If you have an iPod touch, iPhone or iPad with iOS5 and have iCloud on any music you have on one device will move over to the other automatically without you having to do a thing. If however, you have any other iPod, these don't receives updates quite like iPod touches, iPhones and iPads. This means they don't get iOS5 and thus don't have iCloud. If this is the case, in order to sync anything onto your iPod you will need to plug it into your computer and sync it. On the other hand if you need to put something on your iPad, and your iPad does have iOS5 you'll be able sync stuff to it wirelessly.
Proud owner of a 32GB wifi iPad2 iOS5.