The more people miss or wrongly use SF instead of Apache the more I become in
favor of option #1 below.
That's not exactly a clear cut statement given you have made two
different proposals for tidying up!
Also, http://openjena.org/ should probably redirect people to
http://incubator.apache.org/jena/.
It's a bit more complicated than simply adding a redirect at the top level.
The easiest I can think of is have a page that says "Jena has moved" and
redirect all access to http://openjena.org/ to that. That isn't the
friendliest of approach though.
Not all the documentation had been moved so if you want to help migrate
the ARQ documentation that would help. There is also the wiki.
Andy