AFIK there isn't a Nikon Specific monthly magazine similar to the Canon offering.
I think the Canon magazine appeared to appeal directly to a large part of camera market, which Canon users were/are. Now Nikon has a bigger slice of the market, you would think there would be a Nikon specific magazine, but I think that the Canon user base is large enough (they hope) to sustain that magazine, where the Nikon user base may not be. If the Canon mag were very successful, I think there would have been other magazines targeted at specific brands by now.
From the issues I've seen of the Canon mag, a lot of it was not very Canon specific, but it does catch the eye of some Canon users I know.
If you own a Nikon 'professional' rated camera, and register it with Nikon, you can sign up to the
'Nikon Professional Users Scheme', which will get you, amongst other things, a quarterly Nikon Pro magazine. Basically a very nice brochure with the odd hint and tip, but with some excellent pictures. I think the lowest cameras that qualify are the D200/D300. It says on the site that you need to also have a professional level lens to qualify, but I only have the cameras so they may have changed the minimum requirements after I joined. :shrug: