I was reading over John Gruber's thoughts on the keynote today, and he said that you can now make third party messaging apps the default for a particular contact if you want. So if I always message a certain contact through Hangouts instead of iMessage, how do I set that up? I haven't been able to figure it out. I'd also like to make Skype the default way to call a contact if that is possible. Quoted from him: "Likewise, third-party messaging apps can be specified as the default for people on a per-contact basis."