I have a beta of the swap list system ready. To try it out, go here:
http://garden.org/apps/swap/
You can go to your swap list from that link, and add new plants. Should be self explanatory.
You can also import from your Plant Lists over to this swap system, too. When you're viewing your plant list, you'll see a new icon in the actions column. It looks like a swap/recycle icon. Click it and it'll copy it into your swap list and give you a place to enter all the extra information.
I'd be grateful if a few people could start entering in their items they plan to offer for swap later this season. Early next week I'll be working on the actual swapping system.