There's another version of the above trailer
here which features a little "Insider's Look" segment after that explain some of the elements included in the video. Call me a bit old-school, but I'm not sure if I really want random people building cities in the same region as me, and having to work with them on collaborative goals. So I hope there's some sort of single-player mode that lets you just exist in your own world if you want to.
Other than that, totally looking forward to this game. I've been a big fan ever since I played the original as a kid, and still jump into SimCity 4 every once in a while and get lost in it for hours. 2013 can't come soon enough...