I have read that
Hogsmeade will be prepared for the season of Christmas 2009 
, the Castle do spring 2010...
Apparently, the new word on the "street" is that Universal Studios' Wizarding World of Harry Potter will be opening on December 1st, 2009.
While this may excite Potter fans, as usual, Jim Hill Media has given us a clue about why it might not be THAT exciting.
According to Jim's sources, the Harry Potter aspect of Islands of Adventure does appear to be opening to the public on December 1st of 2009. However, only Hogsmeade Village will open with this Phase One opening. Phase Two will open in 2010 with Hogwarts and the Forbidden Forest and the much talked about Flying Car attraction make its debut.
Personally, I'd like to see an all-inclusive opening since we all know this is such a big deal to Potter fans. I suspect that many fans will make a show at the opening and it will be a disappointment to some of those fans to learn that they won't be able to see the entire Wizarding World of Harry Potter.