(I vaguely recall getting both of these Adobe PS books bundled by Sun for NeWS or OpenWindows development, maybe together with the traditional white&green Sun binders and/or the O'Reilly X books.)
I learned enough from the Adobe blue book to do some snazzy printing. (HP PCL for non-PS LaserJets, which I also did, wasn't as cool.) IMHO, PS was a lot of fun, and a good way to be exposed to stack-based programming. (Forth also looks like it'd be fun, but PS had the visual construction aspect.)
Looks like the blue book is available at: http://www-cdf.fnal.gov/offline/PostScript/BLUEBOOK.PDF