I don't want to give away any spoilers for 28 Weeks Later since it hasn't been on DVD for all that long, but the ending certainly seemed like a fine way to cap the series. According to some comments made by Danny Boyle, though, the rage virus might continue raging for another movie.

According to quote given to MTV, Boyle already has an idea for a third movie, but he hasn't gone and presented it to the studios yet. So, don't get yourself all fired up just yet. But, it's good to know that it's a possibility. It would be good to have some more decent zombie-like (the rage virus doesn't make zombies!) action. Especially after Romero's last flick, Diary of the Dead was worse than having your leg torn off and eaten by an undead gas station attendant.

From: MTV