The obituaries for Tkinter are premature. Tkinter has been spruced up quite a bit with version 8.5. Also, Python3.1 ships with the extented widget set ttk that includes a treeview widget.
Ttk comes with 17 widgets, 11 of which already exist in Tkinter, but are improved: Button, Checkbutton, Entry, Frame, Label, LabelFrame, Menubutton,
PanedWindow, Radiobutton, Scale and Scrollbar
The 6 new widget classes are:
Combobox, Notebook, Progressbar, Separator, Sizegrip and Treeview
For additional info see the Python27 or Python31 manual