I had never noticed this menu item before on KernelTrap. It is quite a nice feature. However, when I click "Printer friendly" version on any man page, it only renders the very bottom of the Man Page.
I'm performing an on the fly conversion of the man pages to html using a series of custom crafted regular expressions. This is done with Drupal's filter layer. Unfortunately, it appears that the module I use to build printer-friendly pages is not properly using this filter, and thus there is no printer-friendly version of the man pages. I've disabled the printer-friendly link on these pages for now, and will restore it once I've had time to fix the print module to behave well with man pages.