I am re-working my way through Wicked Wordpress Themes Book, and am struggling to build my own Widget, (end of chapter 6)
After working through the chapter and the code without success, I eventually just pasted the downloaded finished code page from the code archive for author-data.php into my widgets folder in my thematic child theme, but the widget doesn't show up on my interface.
I first visited this a year or so ago (earlier version of wordpress) and then went on to other things, and I'm sure I got it working then.
I have just come across the same problem.
The auto include has been removed see https://code.google.com/p/thematic/issues/detail?id=131&can=1&q=widgets
There is a simple solution see http://thematictheme.com/forums/topic/custom-widgets-no-longer-work-after-update/
I am sure everyone knows this by now but I thought it this reply may save someone a bit of time searching.