Exciting news today as IMAX have confirmed that there will be "a SHORT, 15 second trailer for Harry Potter and the Half Blood Prince prior to The Dark Knight."
Warner Brothers have not yet confirmed this to be true, so stay tuned for more information! The Dark Knight opens in theatres July 18, 2008 in the U.S. and July 25th in the U.K.
Harry Potter and the Half-Blood Prince will be released in theatres worldwide on November 21st 2008.
Thanks to Michaela via Snitchseeker!
Update: A new video was posted on Brightcove.tv today from last summer's grand opening of the Harry Potter FAO Schwarz store in New York which Rupert cut the ribbon for. It's a pretty impressive segment as it gives an aerial shot of the crowds and some soundbytes with Rupert! View it at this link or download the avi file.
Update #2: Brightcove.tv also recently released their video coverage of tthe Hand, Foot, and Wand Print ceremony which took place on July 9, 2007. You can view their report here! Additionally, there's this video in which Rupert briefly discusses Book 7 at the OOTP Premiere.