I'm also very exited about the new multiplayer feature, but I'm asking myself how mighty it really is. Can you make massive online games with 10+ of players? Can it handle big Maps and a lot of actions like in RTS games? Will it ever really work on mobile without wifi, like in 3G or even edge?
I'm not that great in programming, so I may never program an MMORPG :-D I'm just curious.:)
WebRTC is a promising API, but support currently varies ~ caniuse.com/#feat=rtcpeerconnection
(still can't add links -_-)
Out of mobile browsers, it might work on mobile Chrome, but that's it for now.
Regarding networks, it depends not so much on speed (for a simple game you might need only to transfer several kilobytes of data per second), but rather on latency - neither 3G or edge are known for particular stability.
Generally multiplayer over WebRTC sounds very promising, but I'm interested to hear how sync issues are going to be approached, or if they're going to be left on developer' fault.