Parcellite is small and lightweight, stripped down and basic-features-only clipboard GTK+ clipboard manager.
It is licensed under the GNU GPL v3. Gilberto "Xyhthyx" Miralla involvement is indicated.
Early stages of development
Parcellite is still in it's early stages of development. The SVN version as of January 2009 has clipboard syncronization and the ability to handle both primary (what you select with your mouse) and secondary (ctrl-c) clipboards. The SVN version apperas to be a fully working clipboard manager.
The latest "stable" version, 0.9, lacks copy and primary synchronization.
It is unclear when a new stable version which includes such important features will be released in order to give the majority of GNU/Linux users - who naturally get their software from their distro - access to this technology.
Parcellite stores it's settings all over the place. It stores two files called "actions" and "history" in $HOME/.local/share/parcellite/
All versions of it will crash with the less interesting message GLib-ERROR **: gmem.c:136: failed to allocate 134560056 bytes if $HOME/.local/share/parcellite/history is a zero byte file. The solution is to delete it or switch to some other clipboard manager.
The KDE clipboard manager Klipper is the only real alternative. The KDE 4.X (including 4.2) version is utterly broken, which makes Parcellite a very important desktop application.