Zerocoin, assuming it is a cryptographically secure decentralized blind mix, would have really big implications if it is merged into Bitcoin. Even blind mixes are weak to traffic analysis attacks, but if ALL bitcoins are automatically mixed, the risk of traffic analysis being used to link users will be lower than for any other currency system out there. Volume of coins mixed and number of users is what protects a blind mix from traffic analysis, and you couldn't dream of a better crowd size than all of the bitcoin users and all of the bitcoins. The only blind mix I have heard of being implemented and used in the past was Ecache (I seem to recall it was blind) for Pecunix, which was centralized, weak to seizure, and had a tiny user base as well as fairly small amounts of currency going through it. I have never really thought of Bitcoin as an anonymous currency, despite the way the media reported on it. Rather , I thought of it as being a currency resistant to censorship (because it is distributed and not owned by any single company), and resistant to seizure (because the keys that control it can be encrypted, and even stored entirely in a users memory with braincoin). I definitely see the potential for a system like zerocoin to add "actually extremely anonymous" to the list of characteristics of bitcoin.