TfL publishes data dumps every now & then. The first one was in response to an FOI request & covered 31/7/10 (start date) to 3/11/10.
The second one was published in June & covers 1/11/10-31/5/11.
If you drill through the TfL website, you get to the Developers section & the data is in there.
I’m not sure if the first file is still available on there, but a bit of searching around the net will probably find it.
If you speak to Oliver Obrien at CASA (http://bikes.oobrien.com/?city=london) he might be able to furnish you with details of the average number of bikes in the system each day.
You can then calculate availability, usage rates, revenue generation (from the length of hire – unfortunately you won’t be able to calculate the access/membership revenue) and distances travelled. You can also calculate the average cost per hire (possibly even per mile travelled!) by using the headline figures for cost of scheme (after sponsorship income) – a quick search around the web will give you those figures.
How’s that for starters?