Eric Sink had an incredibly timely post on "The Eventual Death of Developer Magazines" in which he noted that print publications such as Dr. Dobb's, Software Development, and Visual Studio were becoming thinner and thinner. Things were even worse than he noted, though, since the magazines held a certain portfolio length and devoted more and more "advertising pages" to unpaid ads for in-house projects such as conferences and other magazines.
Of course, the major issue with developer magazines is that they have not adapted to the Web. There are all sorts of reasons for this, but one that has gone largely unremarked is that the developer magazines (except Code Magazine) are all put together by old folk like me. At 42, I don't consider myself particularly old unless I'm playing Ultimate Frisbee, but when I took over Computer Language, I was 26 and I was taking over from J.D. Hildebrand, who I think was 29. Our competitors at Dr. Dobb's, Jeff Duntemann's company, and R&D, were a little older, but not much.
The thing about young editors is that they create magazines that have a feeling of discovery, because the staff is not convinced that they know everything. They don't know how the magazine "must be," they don't keep columns out of nostalgia and inertia, and they haven't gotten over the passion for creativity and the thrill of power when a technique is explained clearly.
In the particular case of developer magazines, there is a myth that what makes a magazine popular is that it's an "invaluable aide to the business of developing software." (That's not a direct quote from anyone, but it's so absurd that I can't write it without sarcastic quotes.) Dr. Dobb's Journal, which launched with the boast of "Running light without overybyte" has long changed to "Software Tools for the Professional Programmer." From the day I took over Computer Language, the advertising side pushed towards the momentous day when the magazine had not a line of code, a day which thankfully came to pass long after I'd left the top of the masthead.
What makes a magazine popular is ... well, I could write a bunch of stuff about "shared passion" and "personal but authoritative voices" but that would just be old-farty of me -- what makes a magazine successful is exactly what makes blogging successful. Same thing, different era.