The Olympic Park can today boast its first completed venue (assuming we're not counting an electricity substation as a venue). It's a viewing platform built from shipping containers, in the best Lea Valley tradition. The brightly coloured protuberance is hard to miss up on the Greenway, an old cycle path that cuts through the Park and provides the best opportunities to watch construction. The new building acts as a viewing point (slightly cringerly, they're calling it the View Tube), cafe and a community centre (presumably in legacy, right? - the only communities we've ever seen on the Greenway have beaks).
Map http://www.flickr.com/photos/dgeezer/4110866504/
In Pictures: The Olympic Park View Tube - Londonist