According to DanRadcliffe.co.uk, Daniel Radcliffe has been confirmed and signed on to star in the last two Harry Potter films: Harry Potter and the Half-Blood Prince and Harry Potter and the Deathly Hallows (book due July 21, 2007).
From the website:
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.
The fifth film in the franchise, Harry Potter and the Order of the Phoenix will open in theaters (including IMAX) on July 13, 2007. The final film, Harry Potter and the Half-Blood Prince is scheduled for a November 21, 2008 release.