This is what I call a good news day! ^_^
Warner Brothers has confirmed that the teaser trailer for Harry Potter and the Half-Blood Prince will debut via satellite next Tuesday evening, July 29th! If you are a very technical person, and can understand satellite feeds, more information is here!
However, as has been the case in the past, the trailer will more than likely debut online shortly after the satellite airing. Not too long now! Credit to Leaky for the news!
Update: Word is now out via BlogHogwarts that AOL will be debuting the trailer online exclusively on Tuesday!