Ok, got some more DVDs with digital copy today, and it is quite laughable.
One is of course Sony, so thats pointless unless you own a PSP, as I already know.

The second one is a Dreamworks release.
This one will work with iTunes, and Playforsure devices.
My Archos is Playforsure compatible, but I will be damned if I can get it to play the file.


The third disc is a Universal title.
As of yet, I have not tried it, so cannot confirm whether it works or not, but on the paper that comes with it, it says "Not compatible with iTunes".

So, the Dreaworks one is the only one of the three compatible with the iPod/iPhone by the looks of it.
The Sony one is only compatible with the PSP.
But the Universal is compatible with neither.