The issue is there are two 'official' ways of parsing the blockchain for MSC transactions, called Class A & B, one involves parsing bitcoin addresses (see maran's impl of class A parsing @ https://github.com/maran/mastercoin-ruby/blob/master/lib/mastercoin-ruby/simple_send.rb ) and the other involves signing messages with a special metadata message type (class B, cant find impl anywhere but its in the spec https://github.com/mastercoin-MSC/spec#class-b-transactions-also-known-as-the-multisig-method )

All the current block explorers and wallets use Class A parsing, which is now deprecated... I think we can do some server side magic though, but I'm assuming we should just go ahead and implement the class A stuff, it doesn't look difficult and everybody else is doing it :X