Harry Potter (Daniel Radcliffe) and Director David Yates will be answering your Half-Blood Prince questions live on BD-Live tomorrow at 3pm ET (7am AEDT), and we'll be liveblogging it.
If you want to check it out yourself, you'll have to have a copy of the movie on Blu-ray and a Blu-ray player that supports BD-Live. If not, just check out Giz tomorrow when I give you the highlights live.
Update: Here's the link you can use to sign up for the screening. [Warner Bros BD Live]