Eliot Kimber reports [1]:

I've gotten my DITA specialization tutorial far enough along that I
thought I could publish it safely. The tutorial is now available in HTML
and as a downloadable package (including all the source content and
whatnot) here:  http://www.xiruss.org/tutorials/dita-specialization/

I always welcome comments and corrections but since this is still a work
in progress, I really want constructive feedback that will help me make
the tutorial better.