This software would not completely automate CL posting (due to image verification) but would greatly simplify and cut down time required for posting.
The application will have a user-friendly (but simple) Windows interface. You must be familiar with CL ad posting process and problems that arise.
Here I will describe in basic terms what the app will do:
1) It will goto the posting URL in craigslist for a certain category. It will click thru all the formalities. It will fill out the ad form with pre-prepared text.
2) It will display Verification Image in a small box in the windows application. After the user fills out the box, the app submits the verification code.
3) Another small component of the app, will automatically check IMAP-compatible free e-mail and will open the confirmation e-mails and click on the confirmation links
4) Full proxy HTTP and HTTPS support.
5) Another small utility to quickly generate free e-mail addresses
6) You need knowledge and experience of how to repost the same ad multiple times.
7) Ability to post to many cities simultaneously.
That's about it. Obviously, this will take some coding skills as well as experience with craigslist advertising.
Good Luck & Bid away :)
The finished product. The source code. Successful testing of the finished product.
Windows + possibly some Unix scripting