The Mac is alive and kicking for one key reason: money. Last quarter, Apple sold almost three million Macs, 33% more than in the same quarter in 2009 -- the best non-holiday quarter in Apple's history. Those sales generated US$3.76 billion in revenue over the quarter, or nearly a third of Apple's overall revenue. Keep in mind this was during a quarter when the Mac line was stagnant in terms of features, with no updates to any Mac until just a week before Apple reported its sales results for the quarter. The typical post-holiday sales slump and excitement over the iPad also failed to make any serious dents in Mac sales.
It's true that as far as innovation and attention are concerned, the iPad and iPhone are in the spotlight right now while the Mac is on the sidelines. But that's perfectly reasonable considering the current state of the market. Years of ad campaigns and the "halo effect" from iPod/iPhone sales increased sales of the Mac far beyond where they were ten years ago, but even after years of growth, the Mac still accounts for no more than 11% of US PC marketshare, and about 5% worldwide. It's a comfortable niche to be in, however, with research claiming that Macs account for 91% of sales of "premium" computers costing over $1000. I'm sure Apple is quite satisfied with the state of the Mac -- in terms of overall marketshare, it's probably given up on ever cracking 15%, but in terms of the premium PC market, Apple can afford to rest on its laurels for a while.
The iPhone is a different story. Competition in the smartphone market is incredibly fierce right now. For the moment, Apple can afford to be sedate with the Mac as a platform, but it doesn't have the same luxury with the iPhone. No company has delivered the kind of "shot across the bow" to the Mac that Google aimed at the iPhone during the I/O 2010 conference. The Mac also hasn't been the target of 250,000 hyperbolic linkbait articles bashing it for being a closed, dictatorial platform. In order to keep the iPhone at the front of the market, and in order for both developers and consumers to continue supporting the platform over competitors like Android, Apple has to devote more resources and attention to the iPhone. Perhaps next year the balance will shift, with Apple focusing on the Mac more than the iPhone for the same reasons. As Steve Jobs said in an e-mail to a developer concerned about the status of the Mac, it's just the normal cycle of things.
Apple's intense focus on the iPhone this year doesn't mean that the Mac is a dead platform; instead, it means that Apple is comfortable enough with the Mac's status that it can afford to let the Mac just be for now. That doesn't sound like a platform on its deathbed to me. It sounds like a platform in its prime.