I recently had some discussions with a customer on this subject, so I thought I'd post the following:

http://www.g4tv.com/techtvvault/features/25413/Biometrics_Truths_and_Fictions.html

My take: it's going to be a while before biometrics are commonplace, and before we get there, some serious thought needs to go into whether biometrics alone should ever be used as a replacement for other, more seasoned, security technologies.