We are very much against implementing automatic PGP encryption as it actually does not benefit security. If law enforcement were to compromise our servers, then they could get a copy of the address before encrypting it to the vendors PGP key and circumvent that measure effectively, this would then lead people into a false sense of security. As I have said, we are exploring this suggestion further but until we can resolve some of the problems it poses then we will not be implementing it. Multiple options could be integrated, but I believe right now the time could be better spent in other areas allowing bitcoin clients time to better implement multi-signature transactions into their base code and therefore when the time comes it is a more accessible part of transactions we can then place it as a higher priority.