Multi-sig tx execution ideas

I just posted BIP 0010 to gist : https://gist.github.com/1321518

The goal is to provide a standard method for proposing how to spend multi-sig TxOuts, and collect signatures without actually having to understand BTC under-the-hood. I envision, even without any program installed, moderately-interested users could figure out this process without a third-party. The addition of an installed program that automatically detects .txdp files and intelligently presents the information to the users, could bring this functionality to even more users. Perhaps I'm too optimistic, though...

This is, of course, open for discussion/improvement. I've talked briefly with Gavin about this, and he suggested Base64 instead of hex for the block-encoding. I'd lean towards Base58 because developers already have it in their codebase. Also, the separation of fields by underscore characters could be changed. Spaces would make it easier for C++ to read them in using stream operators "<<" and ">>".

-Alan