(BLOUIN) ARTINFO.COM

Arts site also covering fashion, travel, music... and with numerous branches around the world - really worldwide! - the UK site is here. But the visual page(s) are good for a lot of the smaller shows. 

contemporary art forum, art reviews and culture
http://www.worldwidereview.com/forum/
http://www.worldwidereview.com/forum/viewtopic.php?f=12&t=88512