It’s not implemented yet, but the network can support a transaction that requires two signatures. It’s described here:
http://bitcointalk.org/index.php?topic=750.0
I can’t believe I didn’t find that in my search before posting. Thank you.
As you say in the linked post, the escrow is implemented in software (running on the nodes, I presume), so in theory the network can support a transaction that requires n signatures, where n can be any number. Is this correct?
If so, can the network also support transactions that require a majority of signatures (instead of all registered signatures)? For example, the buyer generates three keypairs—using one to initiate the transaction, saving one to release the funds, and distributing one to an arbiter trusted by both parties. Either the buyer or the arbiter could then release the funds.
Thank you again,
-Dave