Some of the updates have included possible posters from the film; all of which turned out being fake or fanmade. But we're not deterred, and have again been alerted to what looks like the first poster for Half-Blood Prince.
Harry Potter and the Half-Blood Prince Poster Preview
I received a nice update today from (anonymous):
Me and a few friends were at our local in Boston UK when we saw this poster.
As a huge Harry Potter fan i know the poster hasn't been released yet so i think this is new.
If real, maybe WB will have something available momentarily. Doubtful, but possible.
Harry Potter and the Half-Blood Prince
Harry Potter and the Half-Blood Prince opens to theaters November 21st.