I am desperate to fuel this bubble, but finding it a complete bugger to buy bitcoins.
(This was in 2013. I bought my first bitcoin at $55 a piece, annoyingly I only invested ~$100 at the time :/)
Halifax were happy to do so though, also 2013.
I do believe the technological possibility is baked in BTC for 3-way signing a transaction so that a validation requires 2 sources of signature. You could implement an escrow system this way.