I recently bought a Pentax K-x because apparently it works fine with all Pentax lenses that I used on the K1000 I had in the 80's. True enough, they do; they snap right on without any kind of adapter, and I can even meter through them. As a bonus, the anti-shake mechanism built into the camera works with these old lenses. I'll post some pictures taken with these lenses when I have more time.
What's also interesting is the fact that Pentax is re-using a name from a classic Pentax, the KX.
Here's the first KX from the 1970's:

Here's the modern version from 2010 that I just bought:
