GForum has been generating a temporary ID all along to keep track of attachments (due to that fact that there isn't a post to attach attachments to yet when you upload one). The only change needed was to store this unique post ID in the post table along with the post, and then prevent a post if that ID already exists. The ID is made up of 35 random characters - I think 64 ^ 35 ought to yield enough different results to not hit duplicates accidentally :)
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com