Jerry - there are now 3 levels of memebership. F is a Forum membership in which you can post and reply to messages for a small fee (or be grandfathered in). This new level of membership is in response to the spam attack(s) we've had recently. The F level of membership folks can't post to the Gear Swap and can't read articles (I think I have that correct). Their forum participation is equivalent to what the non-paying members used to have.
edit - I was a bit wrong. So much for going from memory and not reading the fine print. F members can post to Gear Swap.