I don't think it's against the rules...here's a recent thread on the topic:
http://forum.purseblog.com/ebay-forum/using-tpf-membership-sell-bag-ebay-does-have-197903.html
I've only recently started adding to my ebay listings that I'm a PF member, but I don't list my username. Then again, I use the same username for both...LOL... ush: I think it's all about personal preference as a seller. And as a buyer, it's about doing your research no matter who the seller claims to be.
I agree on all counts! And I don't list my user name either, but I think it's pretty obvious! LOL :shame: