I emailed Air Tran b/f booking our flights (I did this with several air lines as we are travelling with a double stroller and 2 car seats) and they answer I received was the same as stated here - if you gate check them, there is no extra charge and they do not count towards your luggage count. However if you choose to put them with checked luggage the same fees as extra baggage will be incurred. These are all listed on their website based on size and weight.
__________________
Lisa My Countdown Counting down to: Saratoga Springs Here We Come We're living the magic!
My Previous Trips WDW Jan/Feb 2011 - Summer Bay Resort, WDW Jan/Feb 2010 - Pop Century, Jan 2009 - Cypress Pointe Resort, WDW Feb 1995 - Vistana, WDW 3 times (1974-1980)