When using the post editor, the posts in the thread are shown below (at least, they are in the RTW skin). If you write up a post, and then use the "Preview Post" button, you will not only see your post in all it's tagged glory, but the thread's posts will update accordingly below the editor. I usually preview before submitting, to proof-read my post as well as check for new submissions.

I wouldn't mind some form of RSS feed mechanism, but I don't know how much effort or bandwidth that would take.