According to Previews Magazine, Topps has follow-up sets scheduled for June for both their American Heritage and UFC brands.
American Heritage: Heroes Edition appears to be following a similar path to the original set: old school Topps designs for old school folks that helped shape American history. The basic breakdown is two autographs or relics per box, six inserts and eight parallels. There will be eight cards per pack and 24 packs in a box. No details were given as to the subjects, signers or memorabilia that will be used, although my guess is that those who liked American Heritage are going to think the same about this set.
Topps UFC 2009 also seems to be much the same. Small boxes (16 packs), emphasis on autographs and memorabilia. Maybe this time Brock's autograph will show up.
I'll keep my eyes peeled for more info as it is released.