Built into the Copyright Act of 1976, the Copyright Act, is the right of First Sale. First Sale powers eBay, Craigslist, used bookstores and garage/flea market sales all over the country. Essentially the right of First Sale says that if you bought something, you can do what you want with that item, even resell it!!! and not pay the original creator another dime.
Obviously copyright holders are no fans of First Sale doctrine which is why ebooks and digital music should be such a crowd pleaser amongst those who earn their living based on first sales of their items. There is no way, really, for a purchaser of ebooks or digital music to legitimately resell their purchases. This is one argument readers make in pushing for lower prices.
Bopaboo is a new entry into the digital social club market which seeks to carve out a place within the First Sale doctrine for digital purchasers. Is it lawful? Time and lawsuits will tell us.