Because every rank has squares on the 1st or 8th rank, there can be no pawns on the board. Total is 28, so at least 12 pawns have to promote, and no more than 4 pieces have to be captured (most likely going to be 4 pawns).
Seems like quite the challenge, I'm on it :p
Round 10 has ended (in fact, time expired more than 18 hours ago), so it looks like I won. I'm actually somewhat disappointed at that, mainly because my solution was so long-winded and should have been beaten. This was more of a "victory by default" that resulted from a tremendous lack of participation. Oh well... here are the conditions to be met for round 11:
1. All border squares (that is, all squares on the 1st rank, 8th rank, a-file, and h-file) must be occupied.
2. All pieces sharing a file must be the same color.
3. All pieces sharing a rank must be of the same type (i.e. rooks, knights, queens, etc.).
The start time is 1:53 p.m. PDT on April 24. On your mark...get set...GO!