your widget sounded great, but i am sorry to say that it does NOT WORK with any of my 2.3.3 wordpress blogs and themes...NONE
with default and classic theme the sidebar with navigation (=categories) does not show up at all.
with my favorite personal wp 2.3.3 compatible theme THE WHOLE BLOG DISAPPEARS, thus i cant even tell you what i see...source is blank, no header no body nothing!
this applies to all tested browser (opera 9.x ff 2.x ie 6+7)...sorry
i really think your widget is something really really useful for many bloggers, if it works...someday hopefully ;-)