MSN has posted a series of video's of author's reading from their works. J.K. Rawling read a bit from Half Blood Prince and then took some answers. She confirmed that Dumbledore will not pull a Gandalf. When questioned further, she plainly stated that Dumbledore is dead, and that the people over at www.dumbledoreisnotdead.com will be greatly disappointed.
So, could he pull on OBI? Watch the video.