I've reached a milestone in my project, having finally incorporated multisignature escrow transactions into my open source bitcoin marketplace. The first transaction to go through on the new test site is here: d99ad50f20b1f6441dd7fb569fd3c1d26a52fc3a48d865d2bfd2b437eef70a72
It's written in PHP, and uses a full bitcoind node to parse the blockchain and learn about transactions. Users will need to run Bitcoin Core or use coinb.in/multisig,or multisig.info to do their signing.
The code is fresh enough, but works! I've got a site running on the mainnet,
http://test.bit-wasp.org.
Code is on Github for those who are interested:
https://github.com/Bit-Wasp/BitWaspA post on the forums, with a bit more detail:
http://bit-wasp.org/index.php/topic,215.msg1327.html#new