According to fan site www.danradcliffe.co.uk, which professes to be "an endorsed and recognized" (by the actor) website, Daniel Radcliffe has signed for the last two Harry Potter movies, Harry Potter and the Half-Blood Prince and Harry Potter and the Deathly Hallows:
I am pleased to inform you that it has been confirmed for us by Dan's Publicist that Dan has, in fact, signed on for the last two Harry Potter films. Dan will begin filming in September on "Harry Potter and the Half Blood Prince". He has also signed on to return and reprise his role as Harry in the very last film, Harry Potter and the Deathly Hallows. This will "mark a place" in history for Dan and fulfill his wishes as he stated more than three years ago that he would like to portray "Harry" in all of the films.
As you know, it had been speculated in the media that Dan may not return to reprise the role of Harry after it had been published by several media outlets that Warner Bros. were upset with Dan's latest career choice in EQUUS. Warner Brothers quickly put that speculation to rest, and published an official press release confirming they were completely supportive of Dan's projects.
Harry Potter and the Order of the Phoenix (aka Harry Potter 5) arrives in conventional theaters and IMAX on July 13th, 2007.