I reckon they’re set to become an item. Just finished reading Harry Potter and the Order of the Phoenix today, and the bit of interaction near the end just has me suspecting… nothing like starting a rumour. You can read more rumours—and responses—on the J.K.Rowling Official Site.
Looking forward to the next movie (might even go gold class this time), and a new novel later this year. Gotta love the Potter series, loads of fun to read 🙂