Originally posted by Nass Canon and Nikon both have features and glass that are better than Pentax. Pentax is relatively speaking the "value for money" player out of those three. There, I said it. Aneurisms to follow.
In all serious, that doesn't mean that individual components within the Pentax chain arn't better than individual components within either Canon or Nikon. And vice-versa. Horse for courses.
But to judge anyone by the brand they carry makes about as much sense as thinking Leica users must all be amazing photographers. Where's that hilarious video again, of that Leica carrying dude shooting with a lenscap on?
=)
I would say more that Pentax is a niche player, a photographer's camera company. For whatever reason, they have focused on weather sealing, compact size (both with regards to lenses and camera bodies).
Truthfully, Canon and Nikon both offer cheaper lenses than Pentax, although sometimes quality suffers a little bit as a result.
I think Canon/Nikon both have better marketing machines, pay high end photographers to use their gear and have better placement in stores (at least in the United States). There is definitely a perception out there that "real photographers" use Nikon or Canon. Not that I hear that from professionals, more from the masses who don't really know what they are talking about.