Guys, the fork will NOT create two independently usable altcoins -- even if the blockchain splits into two branches that survive long enough to play with.  

Some clever bitcoin hackers may be able to create transactions that are valid on only one chosen branch.  However, most transactions issued by typical users will be executed in both chains;.  Thus they will not be able to "see" the two altcoins.  When one of those transactions, by accident, turns out to be valid for only one chain, the client will either not notice ever, or will get confused, and maybe end up with his wallet in an inconsistent state, maybe even lose coins.

Therefore, there will not be a functioning market for both versions; it would only cater for those clever hackers. Malicious hackers may be able to exploit the confusion of some ordinary clients to do double spends; but payment processors and exchanges will almost certainly deal with just one "bitcoin", the one with mining majority.