I just tried it -- it's working for me.  We've had a much bigger surge of interest than expected for an alpha test, and our server is struggling a bit to keep up.  (We're a non-profit, so no big venture bucks for us -- our geth node is just running on our showing-its-age-a-bit server...)  Give it 30 seconds to a minute -- it should load, it's just a bit slow!

If it's not loading at all for you, I can help you troubleshoot.  What OS/browser are you using?  All our testing so far has been done using Chrome (and a tiny bit of Firefox).  It should be cross-browser compatible of course, but I can't promise it is 100% so just yet