I do! Although not as much as I used to.
Until February, when I was laid off due to budget cuts, I worked as a reporter and photographer for one of the larger daily newspapers in Iowa. My impression from being around other photogs (from multiple papers) at the time was that almost 100 percent use Canon. I think this is both because Canon has a good services program and that they wine and dine the photo staffs at these papers, give them 5D Mark IIs to try out to see if they like them, stuff like that. Their typical setups that they would take out in the field at my papers would be two cameras, one with a 16-35 and another with the 70-200. I believe they mostly used Canon 5Ds, though at the end Canon 5D Mark IIs had started arriving, and I think they used the 1.3X crop camera for a lot of their sports.
I think press photogs also like full frame because it gives them the wide angle perspective that they loved to use from film. This makes sense, as so much of photo work actually involves placing someone in a scene, so it helps to have the wide angle view.
I used Pentax while at the paper because I was not considered a part of their photo staff, so they wouldn't give me any of their good stuff
, and I refused to use a point and shoot (a bad point and shoot at that, until they eventually updated to Canon G10s at the end) when I knew I could do better with my K10D/K20D. So really it was just stubborness on my part, and I imagine it's that way with other PJs who use Pentax as well.
From my experience using the K-7 for freelance, I think it would be an excellent photojournalism camera, a really large step up from the K20D in this particular type of shooting. It'd be nice if Pentax would come out with a full frame, but I don't think that'd win the heart of directors of photography for newspapers anyway
Here are some of my pictures (psst, I used prime lenses for four of these shots):