I mentioned this on ruby-lang already, but just so more folks get the word, svn+http is now available to provide read-only access to Subversion repositories on RubyForge. For example:

$ svn list http://mongrel.rubyforge.org/svn/trunk
COPYING
LICENSE
README
Rakefile
bin/
doc/
examples/
ext/
lib/
[ ... etc ... ]
$ svn co http://mongrel.rubyforge.org/svn/trunk mongrel
A  mongrel/test
A  mongrel/test/test_command.rb
A  mongrel/test/test_redirect_handler.rb
A  mongrel/test/test_response.rb
[ ... etc ... ]

This should be convenient for folks who can't use svn+svnserve due to firewall issues - e.g., your firewall blocks outbound port 3690.

Next up - getting svn+https working. Paul Duncan suggested looking into mod_pam; I've got mod_auth_pgsql2 working so that may come in handy also. We shall see. Anyhow, I think svn+http should do the trick for lots of folks.