UPDATE: The MPAA's official site has been updated with the rating. You can see it by clicking here and searching for Harry Potter. Thanks to Steven for the tip!
Rope Of Silicon and Ain't It Cool News are both reporting that Harry Potter and the Half-Blood Prince has received a PG rating by the Motion Picture Association of America. Surprising, given that Goblet of Fire and Order of the Phoenix both received PG-13 ratings.
The MPAA rated it PG for “scary images, some violence, language and mild sensuality.” We're currently checking this with Warner Brothers to make sure it's legit.
Thanks to Chris, Scott, Geoffrey, and Nizar for the tip!