In case you were actually asking if you can sync your iPad with Ubuntu like we can do it with the iPhone, the answer is no. But Ubuntu does support the application folders like iTunes does. When you'll connect your iPad to your computer, you'll see 2 mount points. One for the pictures and another one for installed applications.
So if you want to put a movie on your iPad, install oPlayerHD, connect to your USB port and in the mount point, you have a folder for oPlayerHD. Simply put the mp4 movie in there. I use handbrake for the transcoding, the quality is really great. Oh it does support all movie formats, but with mp4, you can use the native player.
For music, you'll have to rely on another app than the stock iPod. One is quite good, Fusion Stream. It is actually a dlnp client, compatible with mediatomb, but you can copy your music via USB the same way as movies.
I'm following what the dev team is doing in the libimobiledevice project. Since the last firmware, the checksum do not work anymore on the files. Probably soon, they will fix it.