Not to the best of my knowledge.  There used to be such a magazine a
number of years ago, but the last article I read from that magazine was
strictly Pocket PC or Palm.  However sometimes you may read an article
in a PDA magazine about an HPC.

Charles, the irony is that Pocket PC magazine wasn't always Pocket PC Mag,
it was Handheld PC Magazine.
They changed their name when the global trend of QVGA keyboard-less devices
was really starting to take off.
There are no major publications specifically dedicated to the Handheld PC. I
believe that I heard recently that there was a minor, regional (I believe)
publication in the USA that writes about the Handheld PC. Although I
couldn't give you any more than that on it.

There are some excellent internet resources of course. It depends what
you're looking for from the magazine as to whether that has been transposed
to a web based medium I guess.