At Convention last summer, we had a flyer included with our materials regarding this celebration.
The flyer included the history of the tower and hotel, and until December 14th of this year, rates start at $229 per night. The package includes spacious suite accomodations, a daily continental breakfast, a "welcome" cocktail at the Top of the Tower, and complimentary hospitality suite for groups booking a minimum of ten rooms.
Aside from the plaque presentation in May 2005, I don't think they're going to have any more celebration plans.
I'd love to go, but $229 a night is just too much for me.