I recently came across an interesting app/middleware platform in the google play store for android called musubi group chat. It uses a type of encryption called "Identity based encryption" (first theorized by shamir of rsa fame). It is dead simple to use with all the key management being done without user intervention. In order to send someone an encrypted message you only need their email address (you generate the public key for them). You do need a trusted 3rd party involved but I think that drawback can be overcome. Anyway, if you have android give it a try as I think it is impressive and I'd like to see more apps use this.