[kaoD]

Too bad the Bitcoin protocol is hard-wired to accept at most m-of-3 transactions. More than 3 signatures is considered non-standard and rejected by peers/miners.

[sirsar]

The key, however, can be split an unlimited number of ways using Shamir's Secret Sharing Scheme or a similar protocol.

http://en.wikipedia.org/wiki/Shamir's_Secret_Sharing

[kaoD]

Nice! It isn't quite the same since the spending party will know the private key forever, while m-of-n is a per-transaction signature. Still very useful.

[vbuterin]

You can push directly to Eligius if you want anything up to k-of-20; http://github.com/vbuterin/pybitcointools lets you do that with the eligius_pushtx command.

[oleganza]

Bitcoin is not hard-wired to limit N to 3. Default client discourages "non-standard" transactions by not relaying or mining them, but if you mine them yourself or have someone to mine them, they will be valid and accepted. For all practical purposes, non-standard transactions are just taking longer to be included in the chain and typically required to have a non-zero fee (while the regular payments can be often mined for free).