... is NaughtySVN.
I have joined this project which was started by Alexander Thomas a few weeks ago and I have convinced him that is better to have a release sooner rather than later. The project is still in its early alpha stage[*] but I thought is better to have a rather minimalist and functional client first.
So, I talked to Alexander and we came up with a roadmap; for the 0.0.1 release I am working on the update feature which is about 40% done (update dialog screenshot).
Of course, after the release I will probably make a debian package, too, unless someone else beats me to it :-) .
So, the future is bright.
Update: as a response to a comment, NaughtySVN is designed to be not only a Subversion client, but also a framework for other VCS-es and other clients. It just happens that we are working on the Subversion backend and client at the moment.
P.S.: as curiosity of mine, I have written in python a small nautilus plugin that does the svn update (is a svn frontend) and I must say I really miss the development speed of python when writing in C (or maybe I am out of practice).
[*] only a few features are implemented and can't be used yet as a SVN client without being forced to use another client.
 according to my estimations
 update related code is not committed yet