ok so heres what I know:
There will be teenagers.There might be preteens or middle age.There will be babies,toddlers,children,adults and elders.Young Adults haven't been confirmed yet.You might be able to have your sims take their work home with them/whatever they need to do that was broken at work they'll do at home.You won't have other people coming into your game (you don't have the option to go into someone elses game and no one has the option to come into yours because EA knows it will mess everyones game up)
We will be able to go into other houses.Our sims can walk/run to work.You will only have 1 neighborhood loaded with 90 lots each house loaded with a family and you won't be able to create any other neighborhoods.
There will be: clothing stores,resturants,Cafe's,Movie Theaters,Bookstores hospitals,parks,science centers,Job Sites,Grocery stores,School and a town hall.
It will be released on December 15th 2009 (not confirmed if it'll stay that way)
All the body shapes & facial structures will be in there as everyone knows.In Create-A-Sim we will be able to adjust height of a sim:short,medium and tall.
The traits:There will be 52!
If you need more info try and visit the sims 3 site or
http://www.1up.com/do/feature?cId=3166817