Editra is a relatively new (at least for me) text editor written in Python/GTK.
I have been working extensively with it recently, and although I am not ready to leave behind my currently favorite Python IDE, Eric, Editra doesn't make me miss it too much. One thing that it does that Eric still does not, even though it could, is to provide a code browser for a source file which is not part of a project. I know, many editors do that, but Eric only enables the browser for files in a project, silly thing isn't it?.
Editra has an interesting plugin system, through which it provides most of its goodies, such as the code browser, comment browser, file browser, support for projects, a python shell, themes etc. There is also a plugin for an Ipython Shell that is apparently broken.
Its project support includes source control integration for Git, Bazaar, CVS and Subversion, Unfortunately notmy favorite: Mercurial.
One thing that annoys me is the lack of support for the middle-mouse-button paste, typical of Linux, which I use a lot (on other editors, naturally). I couldn't find the convenient run button as well... too bad.
Overall it is an excellent editor, and I wish it continues to develop well. One last wish: Good code completion, if it can do that it make an excellent alternative to commercial editors such as Komodo. Kudos to its developers!