We were given a demo by Sims 3 producer Mike Cox, he showed us a few things about the game and the new town before we went off to play. He also showed us the new social features. There is no IM style chat feature coming but you can make posts which others can comment on (like Facebook).
There are also a load of new achievements to gain (only for the Base game and showtime at the moment but they may add achievements for other expansion packs). We couldn’t test Simport as they couldn’t get it set up.
But it seems you can throw anything which is in your sim’s inventory at a performing sim or if their inventory is empty you can buy a selection of items from the pie menu. A tour lasts about 12 real minutes (just under 1 day game time)