They are back.

From the Seti@home home page, news column:

September 19, 2004
Early this morning campus got a call from SANS that our web site (this page)
appeared to be hijacked. At that point campus (rightly so) blocked access to
our site at the campus router. As it turns out though, we were not hijacked
at all. Our nightly front page regen script had malfunctioned and produced a
truncated page. This is now fixed.


--
Claude