MyBB Hacks

Is it possible, with the use of xThreads, to add a container displaying all/some of a user's image uploads on their profile?

Here's an example; http://Axil.sheezyart.com/

Yes, it is possible. Probably you can find a similar plugin from RateU's posts, he already created some plugins to do something similar to this (for forums and index at least, IIRC).