<p>If this question has already been asked I appologies, please point me in the right direction.</p>

<p>I was wondering if anyone has any insight into how StackOverflow pops up the "n new answers have been posted, load new answers" thing at the top of a question when you are adding a post. This seems like a very useful function for my forum web-site and I would like to know how it is done. I assume some ajax or advanced javascript of some kind.</p>

Look at this SO blog post:
https://blog.stackoverflow.com/2008/10/solving-the-fastest-gun-in-the-west-problem/
That said, the one implementable
recommendation that came out of this
discussion is an active, GMail like
notification when you are composing an
answer. We agreed with this feature
request, so Jarrod implemented it.
Here’s how it works:
When you start composing a reply, a timer is created.
Every minute, the page checks itself to see if new answers have
arrived.
If new answers arrive, the notification bar will tell you how
many, and offer to update the page for
you.
Answer updates are performed AJAX style, so they don’t interrupt
your current answer.