There are now three projects that I'm aware of that will be built on top of Bitcoin:
Mastercoin,
Counterparty (this one is now live) and
Colored Coins.
Given these are going to affect Bitcoin directly, leverage the Bitcoin network and require bitcoin currency to pay transaction fees, I thought it would be appropriate that either now or sometime soon, there be an additional subforum for these ULPs, separate from 'Alternate Cryptocurrencies'.