Driver’s License

Short answer: No, unless you plan to drive your DL will not be required.

Longer answer: No but it may well be useful as ID/proof of age instead of carrying your passport or as a deposit for audio guides etc.

Is the exact name on your drivers license the same as the exact name (including middle name or initial) on your passport? Which does your ticket match? Beginning some time in 2010 you will need to provide government-furnished ID that exactly matches the name on your ticket. Maybe that would require you to take your DL...

Ken - I never took my DL to Europe when I wasn't planning to rent a car, but I'm glad I accidentally took it last year...

We were stuck in Houston on the way home from Europe right after the hurricane. We couldn't find an available hotel room within 20 miles of the airport, so we were able to rent a cheap car and get to our hotel without spending a fortune.

I now take it with me wherever I go just in case - even when taking the non-stop flights to Europe.

Your passport is your real ID so you don't need your DL. Some people bring it to use as deposit on audio guides or rented bicycles.

You need it for driving to and from the airport, so leaving it at home might not be a good idea. You can leave it with your registration/insurance in your glove box so you have it in case you need it here.

Yes, if you plan to rent/borrow (sometimes, they are free) an audio guide at even one museum. I didn't drive while we were in France last summer, but my license was my audio guide deposit at numerous museums.

Secure Flight is being implemented in phases in 2009-2010. For now, the KGB (oops, I mean TSA) is indicating that small differences, such as leaving middle initial out when purchasing tickets, won’t be a problem initially. At some point before the end of 2010, all airlines will be required to capture your full name from gov't ID, date of birth, and gender when you book.

Remember the ticket name must match the name on the ID you're traveling with. Your DL and Passport may not have the same name (i.e. DL = Jon Smith, Passport = Jonathan L. Smith). Flying domestically, you are most likely to just bring your DL. You need your passport for international flying.

I knew they were phasing this in now, I hadn't heard the date when they were going to start turning passengers away for being ticketed incorrectly.

I assume the airline check in counter will be able to change your ticket, for a fee.