http://blog.mastercoin.org/2014/01/10/master-protocol-%E2%86%92-mastercoin-development-update-2/
Also I saw in another thread that there is a bounty for distributed exchange, and that good progress has been made.
So it seems that counterparty could still be first with a workable implementation, though that will depend on when bitcoin 0.9 is released.
I dunno what is going on with NXT in that regard, if anything. anyone?
hmm i should have been more clear in that update I guess.
you can do dist ex right now, but it is being limited to test mastercoins until a couple consensus issues get resolved. here is one implementation, as you can see their are transactions on mainnet http://mastercoin-explorer.com/order_books
having looked through the xcp code to me it seems the main difference is that the xcp dev (btw you code is very clear and well commented, easy to read for a noncoder like me) is using what mastercoin calls class c op_return transactions, and mastercoin does class a and class b as well, since when it was initially funded way before the pull request that led to op_return being included in 0.9. in that case the xcp code is a bit more rigid, but it allows faster development of a lot of the features in the mastercoin spec.
obviously everything is open source, so folks can borrow from one another and probably do.
rofl @ the guy trying to claim copyright on proof of burn...