Yes, I'm having the same problem too.
I'm also supposed to receive a notification when a new member joins. This evening I noticed there was a new account, created last night, for which I didn't receive an e-mail. Hate it when that happens. I thought it might be my own ISP failing to forward the message, but it sounds like it's a problem with the webhost.
The server was down yesterday which left the forum offline for several hours, so I'm thinking this problem could be related.
With a bit of luck it will all come right again in a relatively short period of time.
If not, I will contact Dreamhost's support team and find out what's going on.