Despite the original plan to open everything in November of 2009, it seems MGM Mirage is now planning to open the complex in stages, starting August 2009 with the first condo tower and going through December 15, 2009 when the main hotel opens.
NOTE: They refer to the main hotel as 'Aria'. It's my understanding this name was scrapped. Also, unrelated - new Vegas Gang going up tonight.
Update: People on the Internets seem to think this name is correct. We'll see I guess. I don't really like the name, FWIW.