My license issued in late 2005 does not have the letter in front of the license number. I am curious about that too.
The fingerprint is just the tip of the iceberg so to speak. Notice the bar codes on the back of your license. Anyone (retailers, thieves, etc.) with a scanner can probably swipe the card and get personal info. about yourself. At least OK no longer uses SSN for license number, but I don't know if SSN is included in the bar code information.
Talk about big brother, the federal govt./"homeland security" has passed a new law to go into effect in a year or so that makes driver licenses a standardized "national ID card" with certain requirements for all 50 states. I read that the changes are going to cost Oklahoma upwards of $500,000,000.00 to implement. The new requirements are causing lots of backlash among the states and may be repealed. Here is a link I found that discusses the "Real ID Act" and its requirements and the backlash.
http://www.msnbc.msn.com/id/15130989/or just Google "Real ID Act" for many articles on the subject.