It's here. The Velodrome scaletrix I mentioned in an earlier post.
I have just seen it advertised on the www.London2012.com website on the shopping pages. It is expensive at £70, but if only my baby nephews were a bit older I would be thinking seriously about it.
As it is I have sent the link to my brother the keen cyclist. I think he will be able to come up with a reason as to why he should get one