I received the following email from DreamHost. Basically they transferred my account to another server with literally no warning at all, breaking a number of things as they did so!
On this new server all my sites run slower, presumably it has lower specs or higher usage. Furthermore, the server they moved me too is one that has been down for several hours (and still is) http://www.dreamhoststatus.com/2009/02/26/some-servers-showing-errors/
So watch out if you want a nice stable service Also, I wouldn't renew too many years in advance if I was you; you never know if they'll move you to a worse server as soon as you're committed to a longer period.