Tk 8.5 was released in December 20, 2007 and brought a lot of new features, including the Ttk.
Ttk is the Tile extension integrated into Tk, meaning that tile themed widget set is part of Tk from version 8.5 onwards.
Bringing support for these new themed widgets will give Tkinter another chance to be the chosen toolkit among its competitors, like PyGtk, PyQt and wxPython. Besides providing new and complementary widgets that make use of platform-specific theming on Mac OS X and Windows to better fit in with those environments, and an improved look and feel under X11, it is the one that is part of Python standard library.

My project consists of:
 - Adding Ttk support to Tkinter, including documentation and short examples.
 - Migrating IDLE to use Ttk.
 - Updating/fixing tkinter demos included with Python.

Project's page: http://gpolo.ath.cx:81/projects/ttk_to_tkinter