We are in the middle of a large update and database wipe. Its not quite ready yet. You might have to reinstall and wait until there is a message on the main website giving the ok before running the updater again and getting ingame. It should be ready tomorrow or in the next few days, whenever the devs get it stable. Until then, uninstall and reinstall if you still have the exe file and keep an eye on the main site for the goahead.
--edit: wow, beaten to the punch...twice!