• I propose that BIPs be wiki pages, with a social convention that the
Author gets final word if any editing wars break out.

ACK 
 
• If he's willing, I propose that Amir take the role of BIP editor.

ACK
 
• I think bitcoin is still too small to have a specialized
"bitcoin-ideas" mailing list; I propose that new potential BIPs be
discussed either here or on the bitcoin-dev mailing list.

ACK

As for what Nils mentioned on using GitHub's Wiki feature, Gavin seems to have started a few proposals at https://github.com/gavinandresen/bitcoin-git/wiki. I think this is the right direction to head in, and a composite list of similar proposals could be maintained on their own repository (to maintain separation from the core Bitcoin repo.)

-Alex