That would require a complicated AJAX solution, as the web page would need to be able to communicate asynchronously with the server to know whether it needs to refresh, without actually refreshing.
There may be a plug-in for vBulletin out there that does just what you're asking for and more, considering that there is a lot of demand for real-time data in this Web 2.0 world of ours.
If we can find a plug-in that we like and feel comfortable with, we may try to implement it. Suggestions are welcome!
For now, all we did was add a simple Javascript timer that refreshes the page every 30 seconds.