The 404 page used to have a meta-refresh tag. Now it apparently has a Refresh HTTP header:
mzmcbride@gonzo:~$ curl -I "http://en.wikipedia.org/wfhsdklfjsdklfj"
HTTP/1.0 404 Not Found
Date: Thu, 08 Mar 2012 04:23:19 GMT
Server: Apache
Cache-Control: s-maxage=2678400, max-age=2678400
X-Wikimedia-Debug: prot=http:// serv=en.wikipedia.org loc=/wfhsdklfjsdklfj
Refresh: 5; url=http://en.wikipedia.org/wiki/wfhsdklfjsdklfj
Content-Length: 5091
Content-Type: text/html; charset=utf-8
Age: 166
X-Cache: HIT from cp1019.eqiad.wmnet
X-Cache-Lookup: HIT from cp1019.eqiad.wmnet:3128
X-Cache: MISS from cp1008.eqiad.wmnet
X-Cache-Lookup: MISS from cp1008.eqiad.wmnet:80
Connection: close
Auto-refreshes/auto-redirects like this are generally considered terrible from an accessibility standpoint. This header should simply be removed.
This is kind of related to bug 17316, but not really.
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=54357