There have been a few posts recently regarding this on
www.flyertalk.com
I copied and pasted
"SWSNA (who is 1 1/2 years). Generally, we do not purchase a seat for her, but take our chances on getting an open seat for her car seat. We can travel with her on a lap, but obviously prefer to get the open seat.
On the outbound leg (two separate flights), both planes were busy. On the first leg, the gate agent asked that we gate check the car seat, because the flight was going to be full. We complied, of course, but the flight ended up less than full (it was probably 5-8 seats short of a full load).
On the second leg (from SAC), the same thing happened at the gate - the GA asked us to gate-check the car seat as we were pre-boarding. This time, I asked directly if the flight was completely full, and he said that it was close, but he "didn't wanted to be bothered" with trying to pull the car seat off the plane if the flight ended up full. I was annoyed (but very polite) and explained that we could move fast if that happened and we would not slow down the turn. His response that it was SWA "policy" that they could not allow the car seat if they wanted. I explained that I was CP, and had never heard of this policy. On the plane, we took A, C, and D (my older child was in D), and no one sat in B (although we did not have the car seat). Again, the plane wound up going up short of full.
After our plane landed in PDX, we were pulled aside by a supervisor (very politely) - evidently SAC had called ahead to PDX because I wasn't happy (I appreciated this extra "service"). After a long discussion, she finally communicated that it was "unwritten" policy that it's the GA's judgment if they don't want to allow car seats. Her explanation was that it wasn't fair to some families travelling with infants if there aren't enough seats for everyone's car seat. My answer, of course, was that this was a new "policy" and never communicated, so it wasn't fair to me. Her suggestion was for us to buy seats for baby SWSNA all summer, since it's going to be busy...."
The basic line is that SW is NO longer just giving you that free seat in all instances. ANd to be honest, it's not really fair to the rest of the passengers. All of us would like an empty to seat to spread out in. If you want a guranteed seat for the child, you need to pay for it!