It's live. (Be gentle!)
The API docs have been updated, but here's the short version:
For Poster.aspx, Tile.aspx or JumpMap.aspx, either pass an HTTP "Accept" header with "application/pdf" or include "accept=application/pdf" in either the query string (GET) or form data (POST).
Since it took a whopping 10 seconds, I also added a checkbox to the post example if you want to generate PDFs from your custom data.
Once any bugs are shaken out of this update I plan to add a link to the bottom of the main map page which offers "give me a printable version" of whatever you're looking at. I could make it either "smart" and offer Charted Space, Domain, Sector, Quadrant or Subsector depending on scale, or "dumb" and spew out exactly what you see on screen but in PDF form. I lean towards "smart".