This came from my husbands office as they travel a lot:

Our travel agent has informed me that starting May 15, 2009, the name in the computer reservation record MUST match the ID the traveler plans to use at the airport. Initially, TSA has built in some flexibility with regard to middle initial instead of full name, and prefixes and suffixes. When you make reservations either with our travel agent or online, you should start matching the information so that you don't run into problems. This will also affect frequent flyer accounts - you should change the name on your account to match your identification.