If you have your site hosted on Dreamhost and your site is down with server errors, you'll probably try to contact tech support at Dreamhost. That can take a couple of hours. While you're waiting, here's a trick you can try which sometimes work to bring up sites that are down on Dreamhost.

Go to Dreamhost and log in to the Web Panel. From the main menu, select "Manage Domains" and choose your domain. Click the link to "Edit" your web hosting settings. Once the edit page comes up, don't actually edit anything, just click the "Change fully hosted settings now!" link.

I think that when you do this, it restarts the httpd deamon for your server so that the changes (even though there are none) will take effect. And this sometimes servers that are stuck and spewing errors. Even if it doesn't work, it'll give you something to do while you are waiting for Dreamhost to get back to you. :)