-A bit like E=mail. When you get a new e-mail and you're on your specific E-mail's site, the new message will automatically pop-up, without the need to refresh the page. Same thing with Facebook, even if you aren't in the tab, an icon in the tab's title will put a (#) next to the amount of new notifications that you have received.
Oh, and forgive me if I mess up the poll choices, for some reason, I never have been able to create a poll without messing up one of the options (i.e. the only option would be 'YesNo')