The trailer seemed like a fake to me at first, with un-simlish music, real world scenes and remarks, and pretty much nothing new. I did think it could be a stuff pack or something, but not an expansion pack. Maybe even some iphone app, like an upgraded version of Sims Social.
Honestly? If I wanted to post stuff about what my sim is doing every second in the game, I could either have keep playing Social, or share my sim's memories as they are. It's clearly some upgrade to Late Night, and not a new The Sims Online (which, by the way, people have been wanting for ages). I'm not trying to be negative here, but I think you can scratch that Animal Crossing way of interactivity. We may not know how this "sim-exporting" will work, but I don't believe it's that way.
I will regardlessly get it, but only for two reasons. One, there's magic in it, and I need as many paranormal stuff in my game as I can get. Two, this expansion's disappointment is balanced with the ever-cheering return of the Laganaphillis (aka Cowplant) to TS3, which kind of compensates it.