Textile Preview allows you to preview the HTML output of the Textile language within gedit, in real-time.
It uses the official python textile package and adapts code from the Markdown preview plugin. Already a few of the planned features from the Markdown plugin are implemented: live previews are standard, and the panel automatically displays when the preview is created.
Currently it's available by SVN, but after a bit of testing, it will be released as a tar.gz.