Matt Corallo posted a modification of BIP 20 in an earlier email and I asked him if he wanted to become the champion of that BIP he submitted.

It is a modification of BIP 20 sans the alternative non-decimal number stuff.

Right now, I will ask the GUI client implementations like MultiBit or Bitcoin-Qt, not different codebases like BitCoinJ or libbitcoin if they support BIP 20 or BIP 21. Feel free to raise any objections.

More weight will be given to GUIs with actual URI scheme implementations and it's good to have a general consensus.