I signed up for the local one here a few months ago and can tell you alot of the issues it seems to have or what it needs.
Things it needs:
Ability to easily strip out personal info, often the emailers do not know better.
A format based email that has in the title Offer, Wanted, Taken, Item. Then a description area for the item('s).
A user data base for the Admins of each local group to see a numerical breakdown of how many times a given user put up an offer or put up a wanted listing. Apparently the wanted listings are getting abused and this would help balance it.
A way for the user to embed an optional photo of the item with the proper auto cropping and so on.
