Also, these are the only multi-sig transactions that will become standard? What about (A-and-B)-or-C tx types? And the only options for (M,N) are {(1,2), (2,2), (1,3), (2,3), (3,3)}? Are 1-of-1 transactions (as silly as they would be) considered "standard"?
(A-and-B)-or-C will wait for another BIP; there are some nifty (and generalizable) ways of doing that by using OP_EVAL recursively that have the added benefit of keeping never-used public keys out of the blockchain.
(1,1) is silly but standard according to BIP 11. It is just a slightly larger version of the standard <sig> <pubkey> OP_CHECKSIG form used by most coinbase transactions.
I think (1,2)....(3,3) combined with all the things that can be done with deterministic keys or "I only have part of the private key" or other tricks will enable plenty of innovative solutions.
Just thinking off the top of my head: what interesting things could you do if you create 3 keys, where the private key for the third is the product of the first and second? If you make them a 2-of-3-to-redeem, is that the same as an (a and b) OR c transaction?