Of course it is. It's not ill-founded speculation, though. If in fact it comes to pass that half of all servers installed in 2007 are running linux, securities analysts (and shareholders) will be asking some hard questions about why Microsoft would ignore half the middleware market.
Yes, the whole article concerns enterprise middleware stuff. "But we dominate the desktop" is not an answer to the problem being posed in the article. Share prices depend to some degree on forecasted growth, and when you already have 90% share of some segment, people want to hear about what you're going to do for an encore. Upgrades are nice, but that's not revenue growth, that's just treading water. It's damned hard to grow a $30 billion company; you have to go take over new markets, and they have to be big.
Desktops in China is big, but you have to convince people that you can get money out of those guys, instead of just having them rip you off. So far there's a lot of hot air in that direction, but little else.
Microsoft appears to be doing OK in the middleware market, but they aren't burning up the world, and that pesky linux just keeps coming. People are starting to ask some hard questions about that; it's to be expected.