Google Calendar (beta at time of writing) uses an Open Source library iText for printing calendars. The calendars are generated as PDF files that can be downloaded to the desktop or straightaway printed.
And this is for the programmers who work under pointy haired Dilberty bosses - the next time you're asked for internet based silent printing of PDF files, ask them to have a look at Google Calendar. You can't get more professional than that. Want anything better? You should think of writing your own proprietary browser (i.e a desktop app) or browser plugin or a Acrobat Reader plugin. Good luck buddy.
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