I'm not sure Apple wants its product integrated into the workplace. They have built their success around being different, not "another option." If you really want integration, you could install gnome or kde and use evolution or kmail, but not everyone's definition of "useful" is "works as an MS client."
Even desktop linux with its superior gui, command-line and numerous compatibility options is struggling to become the MS client of choice. Even if corporates thought they were worthwhile, Apple probably doesn't want its objects of desire becoming a symbol of bondage to The Man.
Apple works well where Apple's software caters for everything needed. Their focus is on creative media and the home. Trying to compete with MS in the workplace would be a losing strategy. If you factor in iLife (and iWork) prices, Macs start looking a lot more competitive despite the high-priced hardware. Most businesses however, don't have a use for this software.
Given the evidence, Apple's current customers, accountants and shareholders would probably suggest Apple *is* doing something very useful for the world. It just isn't concerned with anything MS might be doing.
Having said that, I would like to have seen at least a laser-mouse with proper button-sensors become standard and a macbook-style trackpad for desktop systems.
Icon: I'm not in creative media, so Tux is still king!