I bought the book recently (Textpattern Solutions) and I have got up to speed very quickly, I'm very impressed. Since then I have read quite a few articles on the web that suggest it might be dying a death, nobody seems to be developing it any more. Is this the case. I'm about to start on a very big site and I don't want to use Textpattern if it's dying. Maybe I will get into Movable Type instead as it is now free.
if you google "digital web textpattern" the first result talks about lack of a roadmap.
i ran a 4000 page site on txp but decided to ditch it in the end and switch to expression engine. the latter seems to offer more with waaaay less tags to use and a simpler admin panel. i also found alot of txp plugins did not work properly