There are quite a few good Pentax blogs, but like the good guys here, Pentax seldom attracts loudhailers and exhibitionists types (ie. like Ken Rockwell).
His stuff is usually full of opinions that shifts here and there and very often unproven, sometimes laughable .
Anyway, IMO, its not that important whether there is or not a Pentax version of Ken Rockwell, we pick up photo know how on any good photograph site, whatever brand the owner of that site is using.
I'd like to see myself as being able to see past the brand speak and gear pushing and see the basis of the technique being used.
An example of this is Strobist.
David Hobby does not promote any brand. Whatever it takes to get the effect is the bottom line.
A couple of pretty nice blogs that I know of where the user uses a Pentax (and usually another brand or two).
Pentax K5 Photography by Jim Radcliffe
PENTAX DSLRs
Pentax K-5 | StarvingPhotographer.com Blog
What Blog is this?
Benjamin Kanarek Blog
If you need more info on Pentax lenses and gears. There is here and Pentaxforums.
There is also Fengwei here, who has practically owned every Pentax lens at some point of time.