Very interesting, I wonder if IB is considering going in this direction http://www.economist.com/finance/displaystory.cfm?story_id=11708038
I know of at least one bank in Europe ,which use this technology for couple of years. Not just for online bankning, but also for in-branch transactions.
No good - fingerprints are so easy to copy, or fake using a bit of new skin (wait till tacky, then roll over a toe and you have placed your toeprint onto your finger) or a laser printer on to a transparency can create a mould from a print on a glass. It's all out there on the net. Also, you'd have to keep a copy of your prints as a backup in case you cut your finger........... Also your print could be digitally 'skimmed' by a fake or dual purpose print reader. The Swiss banks do it best with 3 part authorisation, Username, password and a printed, numbered card/list of additional one time codes. You have to enter the right code for the right number when prompted, it is never used again.