Most of my sites were unavailable for a short period of time just now, as a result of what I assume was a PHP-related problem: static HTML pages continued to be served, but anything involving PHP — which I use on almost all my sites –threw a 500 Internal Server Error.
Update, 7:50 PM: From DreamHost:
Some of you may have noticed your site is giving a 500 Internal Server Error. This is due to a package upgrade we are currently performing. We tested it last week on one of our clusters and it went without incident, so we’re not sure why it’s giving problems today. We are working on resolving this issue ASAP.
(I love it when tech support says “we’re not sure.”)
Update #2, 7:58 PM: More on the DreamHost status blog: package upgrades = momentarily broken PHP.