I have taken a tripod through at SFO and will try to find the TSA rule that permits them. (I asked the same Q on FT and somebody posted a link... maybe try using search?) Personally I thought it was idiotic that I couldn't bring my nail clippers but I could bring a heavy tripod.

Also at SFO, I once tried to take my boyfriend's rolly bag to the AC (he had a last minute meeting at work, so he dropped me off with both bags, so he could take BART from work). The gate checker told me that I couldn't take an extra bag and swore that it was AA's policy. I went to the AA counter and they swore it was the TSA's policy. I asked both people to stand next to each other and help me figure out the situation -- they argued with each other and I finally resolved it by stuffing my shoulder bag into one of the rollybags.