While opening all StackExchange sites at once (Opera -> Links), superuser gave me the page that told me there were too many requests.
The title of the page contained "StackOverflow", not superuser or StackExchange though. Did someone copy-paste the file and not change the contents? The e-mail address is still just StackOverflow, too.
I'd like to add for the other sites whether they are doing it as well or not, but I doubt me flooding StackExchange (again) would be well received ;)
(I added the sourcecode to the print-screen...)