I work in construction and there have been some pics and info in the trade press recently about costs etc.
The BMX track for the 2012 Olympics will be housed in the horseshoe shaped stadium at the front-centre of the pic below. You can just about make out the track inside under the shadow.
Apparently the budget for the track & stadium is £11 million and it will definitely be one of the venues that will be retained after the Olympics and not pulled down.
So get practising guys and I will see you on the gate in the 40+ cruiser final for the gold medal!!