I have a couple of servers at rackshack for doing TGP & MGP galleries -- 2 of them are down, 1 is intermittant and 1 is just fine. The only ports open on these are 22 and 80 (ssh and web) - not even FTP - so this is probably NOT related to the sendmail exploit (sendmail isn't even installed on any of the servers).
I just got off the phone with one of the rackshack support people and they can't give any ETA yet as to when stuff will be up, however the guy I spoke with was called into work a few hours early because they are now swamped lol. They also stated it was a network related issue wouldn't comment one way or the other if it was a denial of service attack.
Needless to say, 4 servers with round robin DNS and the ability to add and remove servers from the mix in under 90 seconds really helps
Anyway, just thought I'd share what I know about it...
CGI