Yup- If we have enough interest, this will be an ongoing thing. After a year, you should have enough to make a quilt!
I went back and forth about the size and amount of blocks- but thought one would be a minimal amount of effort, and as KGoodHand pointed out, a 12.5 square mails nicely in a regular envelope.
How this works- let's say that Mary (imaginary lady) and I are partners. Her theme is "scrappy nine patch blocks." I would make her a scrappy nine patch block which is 12.5 by 12.5 inches big. I would then mail it directly to her. Mary would make me one in my specifications and mail it to me. In December, Mary and I would be given a new partner and start over. Clear as mud?