Joel Spolsky incorrectly read the announcement as SD taking over the Dobb's name. Dan Read hopes this might mean a hybrid magazine that combines the best of both. At the risk of alienating my future potential editors, almost certainly not. So far, what we've got looks like the pro forma assurances that are typical of an all-out acquisition. Software Development's Editor, Alexa Weber-Morales, was laid off in December (when she was six months pregnant, to boot). The magazine's being folded in the June timeframe, which means that the "change" will coincide with the build-up to the announcement of the 2007 advertising rates (at least, if the calendars are the same as they were when I left the company 10 years ago). In other words, even with what I imagine is considerable overlap in their subscription lists, Dr. Dobb's will get a circulation boost of 30-50K readers which will allow them to raise their advertising rates. Aside from a bug on the cover for a six months or a year, and perhaps a 16-page internal supplement, that's probably all they will take from SD.
At the most basic level, Dr. Dobb's probably sees no reason to change a winning formula -- they know what they like and they execute it. If Jon Erickson and the editorial team wanted the softer, more management-oriented articles that characterized Software Development, they would have already incorporated that type of writing. As for columnists, I think SD has some writers who are clearly at the very top of their craft -- you may have heard of this Scott Ambler kid -- but DDJ already has a full boat of writers to whom they've always tended to be loyal.
I may be wrong and, facing the travails of the industry, this might be an epochal shift in content. I doubt it, though. There's no new blood.