I think an important step has been made today, with the ability to view (and check out) the SVN repository used by the Eclipse technology project (which includes subversive) over plain old HTTPS, thanks to bug 168282 and the work of the webmaster team.
The rationale for providing it (as opposed to wanting it, which it has been for some time) is that not all firewalls allow generic traffic from inside an organisation to outside the world. Whether that's a Good Thing or a Bad Thing is largely one of personal viewpoint; however, whichever view you have there's the quite common case that large organisations are prevented from going outside of the HTTP space.
Since SVN is supported over HTTP (and for that matter, HTTPS) and that most organisations allow HTTP/S access outside their borders (sometimes doing channel verification, to ensure that traffic over HTTP/80 is really HTTP traffic, and/or putting an HTTP proxy cache in the way) which means that HTTPS is often the only way to tunnel outside of an organisation.
The nice thing about this approach is that you can now download the code from this repository, regardless of the firewalls that you happen to have. You can update to HEAD, do diffs; even create patches for submission to bugzilla.
The reason for having it now is that an Eclipse member, doing work on the technology project, had just such a firewall in place. So finally, because they needed it, it's here.
You can browse the SVN repository at http://dev.eclipse.org/svnroot/technology/. Unfortunately, you can't get anonymous access of CVS over an HTTP proxy (there is an anonymous pserver port running on 80, but since it's not HTTP those that go through proxy servers can't connect to it; and those firewalls also have rules that say connecting via an HTTPS proxy are only allowed to connect to 443). There is a port 443 available for CVS usage, but you need to have login details over SSH as an Eclipse committer to make use of that. In any case, it's a start, and whilst there's no likelihood of projects moving across to SVN en masse any time soon, it's a beacon leading the way for others ...
Update: the SVN URLs have changed (thanks for letting me know Denis!) so I've updated this page for those that come across it in the future.