Doug's version of the Photon light sold by Aeromedix includes a slim little plastic clip that pops onto the light for use as a detachable lanyard.  Take the lanyard string off, attach the clip to the switch-side of the light, and now it cannot be switched on.  Pop off the clip when needed and you can switch on the light.  This is how I carry the yellow Photon in my pocket. 
 
  I realize the Pico Lite approach was mandatory to maintain a reasonable price on the new PSP.  However I prefer the Photon's slim profile, adjustable beam, easy 1-hand operation and (most importantly) lithium cells, so that's what I'll be toting for an ultra small light.
I'm not trashing the Pico, I just wanted to point out that it is easy to carry the Photon and protect against switching it on accidentally.  This approach would certainly be a PITA for an EDC light, having to constantly remove & replace the clip.  But for a dedicated kit light, I like it.