Just read some new info on the Forza site about Forza 4. There's only one major item on the list, which is at the bottom if you'd rather skip straight to it.
First some disappointing (but not unexpected details): Exclusive cars.
1. The Preorder-exclusive car you receive depend on where you preorder:
Amazon.com: Subaru Impreza WRX STI
Best Buy: BMW 1 Series M Coupe
GameStop: Alfa Romeo Giulietta Quadrifoglio Verde
Wal-Mart: MINI John Cooper Works Clubman
Target: Honda CR-Z EX
2. Those who purchase on or near launch day will receive and exclusive set of cars:
Ford Mustang GT Coupe 1965
Koenigsegg Agera 2011
Lexus SC300 1997
RUF RGT-8 2011
Tesla Roadster Sport 2011
3. Limited Edition is confirmed, and while no details are given, it hints at another "VIP" status upgrade for Limited Edition buyers:
For “Forza” fans who crave the VIP treatment, a Limited Collector’s Edition will also be available. Stay tuned for more details on the exclusive content the Limited Collector’s Edition will offer.
4. The cover car will be the Ferrari 458 Italia (at least for the standard retail edition)
5. Profile Import will allow players to move data from Forza 3 to Forza 4
For those who have invested tireless hours in “Forza Motorsport 3”, Turn 10 Studios is pleased to announce a unique “Forza Motorsport 4” feature called Profile Import, which rewards fans for their time. Based on your player level and the cars in your garage in “Forza Motorsport 3”, gift cars will be automatically added to your “Forza Motorsport 4” garage and you’ll also receive bonus gifts and credits. And for those who spent hours creating intricate layers and liveries in the “Forza Motorsport 3” Livery Editor, you will be able to import those layers, so your time isn’t lost!
So all liveries and vinyls will be transferred directly, and Driver Level and car collections will be converted into "gift cars, bonus gifts, and credits". No confirmation on whether this means your garage will be translated as directly as possible, or if the gifts will be reduced to maintain game balance. Either way, I'm pleased with this as long as it leaves my original Forza 3 data intact.
At the bottom it confirms that more information will be announced at E3, which starts on June 6th.
I've posted a Thread in which to discuss all Forza news until the game's release this Fall. Be sure to put that on watch.