seems to be happening to some other people as well.
...just out of curiosity: can you log in to your DreamHost panel, Go to Domains>Edit the Domain you are having issues with.. and tell us what PHP version it is set to use?
I ask because now that I think of it, this past Friday, a site I work on was down. Someone from the company contacted me and said they were having some issues..when I investigated I found that the PHP version had inexplicably been down-graded to PHP 5.2
I assumed a well-meaning but bumbling employee had found their way in and made changes, but after reading all of the issues I wonder if something else might have happened.
upgrading back up to PHP5.4 fixed everything in that case...may or may not be related to what you are experiencing.