We also just returned (6/8) and found the parks (especially Magic Kingdom) to be crowded as well. We've gone the first week in June several times and this is the most crowded I can remember.
We went to Magic Kingdom the first time Sunday morning at 9:00, hearing that Sunday's are generally quiet at Magic Kingdom. We had time for the Carousel, Winnie the Pooh, Small World, and Peter Pan. After these 4 rides, the stand by times suddenly jumped. I'd say it was very busy from about 10:30am on through the entire day.
Disappointed that we didn't get much done at Magic Kingdom on Sunday, we went back on Tuesday night. We arrived at about 6:45 and there were already people lining up on the curbs for the 9:00 Spectromagic. By about 8:15 it was almost like closing time. There were so many people on main street it was difficult to move.
The rest of the parks were better, but the 2 days we were at Magic Kingdom, I thought were very busy based on past experience during the first week of June.