Personally I want it because if access to the site is idle for more than 5 minutes here at work, it blocks me again (damn marshalling software!) and I have to go through a labourious amount of clicks to get the site back up.
In a community sense however, I just think it would be useful so that if something is updated on the site you can see it intermitttently while you work, rather than having to press F5.
I can already see some of the issues of implementing this (refresh during posting and server load strain), but I thought perhaps there might be a way to do it.
What do you think?