I'm Only A Member, so I was not allowed to take photos of Hall decked out as Hogwarts when I had lunch there yesterday. Fortunately, attendees of the DVD launch party were allowed to snap away, and several photos have already been posted:
Hall with "floating" candles (from the BBC Norfolk website)
High Table with Dumbledore's chair (from 'TLC PoA DVD Launch Party Report Part I' by Melissa Anelli. The Leaky Cauldron, 19 November 2004)
Newsround's set photos slide show includes a view of Hall from the Gallery, some close-ups of the replica Honeydukes sweet shop, complete with chocolate fountain for marshmallow dipping,and the sign outside pointing the way to "Hogwarts," not to mention some bigger photos of the Knight bus's arrival than I took at the rehearsal.
Short video clip of the event on Extra TV.com