I had a similar question earlier.
We had not gone for 3 - 4 years and were just there a week ago, so I'll try to answer your question.
Magic Kingdom:
Fantasyland expansion - they've done away with Toontown Fair, and modified it to Storybook Circus. Minnie and Mickey's houses are gone, but Goofy's Barnstormer is still there. They've moved Dumbo from next to the Carousel and put it and a second Dumbo ride there. In Dumbo's former location is a pair of free-standing castle-type archways.
In the new Fantasyland are Enchanted Tales with Belle, Be Our Guest restaurant, Gaston's Tavern, Under the Sea - Journey of the Little Mermaid (ride), and Ariel's Grotto. Also new is the Bibbidi Bobbidi Boutique, in Cinderella's castle.
The Seven Dwarfs Mine Train ride is in the middle of the new Fantasyland and still under construction.
New interactive stuff in some of the standby queues - Big Thunder, Haunted Mansion
Epcot:
Test Track switched sponsorship from GM to Chevrolet, and had a major renovation. Gone are the crash-test dummies and the mechanical look, replaced by a sleek, futuristic look. The pre-show ("let's put up the Belgian blocks") has been replaced by an interactive display where you can design your own car.
There are some new stores and restaurants in the World Showcase, including La Hacienda De San Angel in Mexico, Karamell-Kuche in Germany, Katsura Grill in Japan, Spice Road Table in Morocco, and Monsieur Paul in France.
Animal Kingdom:
Camp Minnie-Mickey and Festival of the Lion King are gone. They will be replaced by the new Avatar land, still under construction at the present time.
Hollywood Studios:
No longer MGM Studios. Star Tours - The Adventure Continues is renovated, and is now 3-D with new story lines for the ride. The Legend of Captain Jack Sparrow is a new attraction.