Just Got back form the London conference. A few thoughts.
* Stefan's talk was great. Looking forward to Bitcoin-JS 0.3 which will bring faster javsacript transaction signing to blockchain wallets (particularly for netbooks and the iphone app). Validating the client side js by bootstrapping with a bookmarklet is also an interesting idea - DOM validation needs to be performed as well though.
* Pieter's talk was also excellent. I'm glad to see that the reference client may move to an unspent outputs database in the not too distant future. However there was no mention of any accompanying protocol changes. If many nodes upgrade and are unable to distribute the full blockchain it will increase the bandwidth requirements of the remaining nodes. Making it even less desirable to run a full node and centralising the initial block download.
* David stated in the U-kash presentation that some customers were validated with full KYC/AML checks. Maybe it would be possible that bitcoin exchanges could be limited to only using only codes with the proper KYC information attached lessening the risk for U-Kash.
* Whoever bought the minrig that is one hell of an impulse buy.
Anyway good to see some people using the app and website in the real world.
The escrow feature was removed because not enough people were using it. I think maybe it was just too confusing/not well documented enough.
Two-people-required-to-spend bitcoin addresses would be a great feature for blockchain.info.
Coins would be sent to that address, then both address owners would have to agree to spend them (by signing transactions).
The incoming coins do have to be fully spent, but it is easy to create transactions that send the change back into the "vault" (multisig address).
This is certainly possible. Assuming that both parties were logged in at the same time the transaction signing negotiation could be done directly over the websocket connection.
HTTP POST isn't among the options listed here.
Sorry Http POST notifications were removed. People were trying to use them for payment processing and they were not reliable enough for that purpose. Skype notifications should work fairly well on the iphone.