While this won't mean much to most people here, as I don't recall there being a very strong Dungeons & Dragons fanbase here, this was a staggering blow for me to hear just now. Having been a child of fantasy and science-fiction, I was raised on a healthy basis of these kinds of fiction, as well as D&D. Among the wonderful books my dad let me explore containing this subject was his substantial collection of issues of "Dragon" and "Dungeon", supplimentary material to the game. Since then, I've collected issues of it by myself.
Really, it's kind of like seeing a party of my childhood die down. While they'll still be technically putting out the kind of material these two magazines would have held by simply going to an online format, it's still somewhat upsetting.
Anyhoo, you can find info about this if you have any desire about this information here and here:
http://www.wizards.com/default.asp?x=dnd/news/20070419a
http://paizo.com/paizo