This is one spec that's often quoted about the K-5/K-7, and that's this mysterious "coldproof to -10 C" or "cold-resistant" feature. Of course Pentax offers no official description of what exactly this means. All they say is it's "a fully weather sealed and coldproof design".
Obviously this doesn't mean it is resistant to
becoming cold. Not only is that impossible, unless it were airtight and covered in a thick thermally insulating material (or vacuum), but the metallic body would probably ensure that it would be the object in your possession that drops in temperature the
fastest. Also, being able to operate at -10 C is not very impressive, considering any dinky little P&S can easily do the same (besides somewhat reduced battery life). People have taken unsealed entry-level DSLRs into far more extreme temperatures.
The only possible solution I can think of is that "coldproof" is a property not of the camera, but of the weather sealing itself. I guess cold can compromise properties of the seals by thermal contraction, or making the rubber brittle. It could mean that the weather sealing retains full effectiveness down to -10 C. I can think of two problems with that theory though. Any precipitation at those temperatures would be snow. The only real way for it to intrude into the body would be if it were to melt into water, which implies that the temperature of the body has risen above 0 C, making the "-10 C" claim pointless. Also, Pentax's wording: "a fully weather sealed and coldproof design" seems to imply that the coldproof design is a separate property.
That or it's just marketing speak: a "feature" that sounds nifty, but is vague enough that it cannot be disproven or used in a warranty claim.
Any other thoughts?