RabbitVCS is a plug-in for Nautilus, The Gnome file manager, that implements a GUI for the Subversion Code Version Control system similar to the way TortoiseSVN does this for Windows Explorer.
As one can see from the comments on the site, this is a much sought-after feature.
The system is written in Python, and the authors indicate intentions to support more version control systems in the future with support for Git already in the works. I will be very happy to see it support my personal favorite VCS, Bazaar, one day.
Rabbit VCS is very programmer oriented, and probably not suitable for common users, one thing I would like to see in Nautilus one day, is a tool that would deliver the benefits of file version tracking to common users, such a tool would need to support not only developer oriented VCS, but also other OS and infrastructure-level facilities such as LVM and Storage snapshots and Backup systems.
Ifblog (ponderings 2.0) 