I think it'll happen by stealth and accretion. Microsoft is focused on the traditional business mindset where the company is the primary entity, but out on the street (and increasingly even in business), it's the people who are important. Apple makes products which appeal to people rather than business, and so more and more people are using those products. After a certain point, the onus is on the companies to support the products that their employees and customers already love, rather than insisting on something different for business reasons.

There's no denying that there are certain business realities which must be addressed: security, tracking, integration with centralised databases for contacts, calendars and so forth - but the actual bar isn't set very high; Apple can support what's needed. The real question is that of mindshare, and that's what Apple is best at. Ten years ago you wouldn't read a review of a new PC and see a Mac recommended instead or as an alternative; today you do. Apple products are exceptionally visible and exceptionally desirable, and that's true whether you're the man on the street or an employee at a company or the woman with IT spending approval responsibility at that same company. Apple believes in taking the products to the individual, and letting social factors do the rest - rather than selling directly to corporate and damaging consumer-level identification and credibility as a result. I think that it's a sound policy, and that it'll penetrate business IT as a natural consequence in due course.