The next time you log into WordPress you will be able to upgrade to version 3.2… maybe. Your website must be running PHP 5.2.4 and MySQL 5.0 to install the newest version of WordPress, and you will be presented with a notice telling you that you cannot upgrade.
So, what should you do, if you can’t upgrade? Get a new host… seriously, get a new host. It was announced almost a year ago that WordPress would need these minimum requirements. Of course, if you don’t want to switch hosts, then you need them to upgrade you.