DITA xml

Does anyone here have experience with DITA xml
http://xml.coverpages.org/dita.html and can you give me a clear idea as
to how widespread a format it is, from reading the coverpages reference
above it sounds interesting, and it has a number of associated
resources, mostly IBM specific, what I'd like to know is how often does
one actually come across DITA xml in any sort of usage?