The new Fallout: New Vegas screenshots have been released online in high quality (one of them was previously released in lower quality, and the other two were only seen in magazines). You can see the new version of Mariposa super mutant in more detail, a super mutant attacking Dinky the Dinosaur, and Primm.
This is what J.E. Sawyer had to say about the new mutants:
The Super Mutant heads were remodeled and the body texture was mirrored so the artist could devote more space to the head texture.”