Yep, I have already looked at the site you linked to. I am a little confused though, perhaps its the website being a bit crap, but I am finding it hard to work out exactly what area and what venues are open. I take it The Shard is not taking part? Do you (or anyone else) know of any other high rise buildings that might offer good photo opportunities, either out of windows or balconies (I guess roofs are out of the question).
I am not really all that interested in the architecture of the buildings, more the vantage points they might offer for panoramic pictures.
I saw a really good photo in a mag, (I think it may have been an advert actually) and it was taken quite high up looking over the Thames near the 02 Arena at nighttime. Would love to know if that building was open...?!