user1853: I have read here about the possibility of Multi-signature transactions. Is there a statistic available how much of these are done?

user153: Blockchain doesn't currently offer that and the only way to construct a transaction like that is to build it manually.  So as a result both the sender and each recipient must have l33t skills.
This capability will come, it is just that since that was introduced, scalability had to take priority over new features for most Bitcoin development.
They happen but rarely.  Here's an example of Bitcoin address used recently (March 5, 2013) in an escrow transaction:
,- http://blockchain.info/address/13MH4zmU4UT4Ct6BhoRFGjigC8gN9a9FNn

1853: <p>I have read <a href="https://blockchain.info/wallet/escrow" rel="nofollow">here</a> about the possibility of Multi-signature transactions. Is there a statistic available how much of these are done?</p>
 153: <p>Blockchain doesn't currently offer that and the only way to construct a transaction like that is to build it manually.  So as a result both the sender and each recipient must have l33t skills.</p>

<p>This capability will come, it is just that since that was introduced, scalability had to take priority over new features for most Bitcoin development.</p>

<p>They happen but rarely.  Here's an example of Bitcoin address used recently (March 5, 2013) in an escrow transaction:</p>

<p>,- <a href="http://blockchain.info/address/13MH4zmU4UT4Ct6BhoRFGjigC8gN9a9FNn" rel="nofollow">http://blockchain.info/address/13MH4zmU4UT4Ct6BhoRFGjigC8gN9a9FNn</a></p>
