Since circa 2000 I've owned Ultimate TV, Tivo, Directv, and DirecTV HD DVRs, and the manuals all described the USB ports as "for future use," there never has been a firmware upgrade to activate them and the new Tivos still won't let you use more than one hard drive, as per Weaknees.com, if you add on an external drive, the internal drive is disabled.
From what I've gathered it appears related to DRM issues. I think standalone Tivo 2s or 3s may have usb functionality, however activation of the usb ports may still be the exception rather than the rule with satellite receivers, although I'm in the US, maybe the situation is different in Canada.
