In message GApao.15874$UD.10773@hurricane, at 07:01:12 on Tue, 17 Aug
2010, Roy Badami remarked:
I had assuemd that these 'bike scheme keys' are RFID devices - so the
terminals must already have RFID readers. So the necessary hardware is
probably already there.

There are many different kinds of RFID. It's not automatic that every
reader can inter-operate with every kind. Indeed, the Oyster readers are
well known for getting "confused" if there's a second and different kind
of RFID in range at the same time.
--
Roland Perry