Computing on Demand reveals how to control a HTPC with a PlayStation 3 remote control, you can read the article over here.
Having recently reviewed the SilverStone Grandia GD08 and loving it, I was
looking for a way to satisfy the one need SilverStone left me with. The case
design didn't allow for a standard 5.25 inch bay device to be used due to the
flip down panels incorporated to conceal your optical drives. This, in turn,
meant that installing the coveted iMON VFD was out of the question; that means
not have the control of my PC from a remote control. In the interest of my
budget ($10, set by the soon to be wife) and keeping my Dremel on the shelf, I
set out looking for an easy way to incorporate operating my HTPC from a remote
control without spending a pile of money, cutting up a beautiful SilverStone
Grandia GD08, or having a keyboard and mouse on my coffee table. After much
research, I found a way to use the PS3 Remote Control I already had to control
XBMC, WMC, or any other application that accepts keyboard input!