The Wall Street Journal has a freely accessible article up about the new respectability afforded the Macintosh platform by the transition to a Unix-based operating system, and whether what seems like an increase in the market uptake for Macs can be translated into success in the business world. I think the article does a decent job of presenting the facts, all things considered - though it does fail to mention that one reason why Macs are being viewed more favorably again is the shift from client-based applications to the web - but in the end I think the optimism in it is misplaced; Apple will screw up this chance to make long-term inroads, for the same old reasons why it always failed to do so in the past.
The fundamental problem is this: Steve Jobs is at bottom a control freak on the order of Frank Lloyd Wright, and his ideal world is one in which you buy Apple hardware and Apple operating systems to run software written primarily by Apple exclusively for Apple's OS; any deviation from this viewpoint would strike the man as heresy, as dangerous as drawing satirical cartoons of Mohammed and hand-delivering them to your local mosque. The surest evidence for this is that Jobs and company have so far failed to do what any half-thinking person moving to an Intel-based architecture would have begun doing right from the start, namely working with groups like Xen and VMWare to provide support for running Windows within OS X in the same manner as has been done for OS 9 "Classic" (only better, and at native speed). Far from doing anything so sensible, of course, Apple has instead adopted a brand new firmware architecture incompatible with the traditional Wintel BIOS, and has then failed to provide even the slightest technical assistance to those looking to dual-boot Windows on their new Intel Macs; this sort of thinking may be working well for Steve Jobs with the iPod, but for a computer platform so far behind in the application availability stakes, it's the kiss of death - or rather, of asymptotically declining market share. And I haven't even begun to touch on the inanity of making the obscure Objective C language the primary development language for OS X, as if most developers would willingly forfeit the time to learn it in order to target a mere 2% of the global PC market ...
The Mac's biggest saving grace is that Bill Gates needs to keep a token competitor alive to fend off antitrust efforts, which is the only reason why Office keeps being shipped for it; running a distant second after this is the ability to draw on the vast amount of pre-existing open-source software written for the likes of Linux and FreeBSD. Were it not for these two things, the Mac as a computing platform would already be dead, and even with them it's the iPod keeping the firm in good health, rather than the premium-priced computers it was founded to sell. The shame is that OS X is actually a pretty good platform, regularly updated with useful features people are willing to pay for (unlike the ever-receding "Vista" of a certain monopolist), but Jobs' fixation on a closed ecosystem will keep it from ever achieving the level of popularity it truly deserves.
PS: On a related note, check out the following article for a different take on the OS wars. "30 Years of [Freedom from] Apple". I think if you're honest with yourself, you'll have to grant that he does have a point.