Another consideration is the availability of software. There aren't that many things the average home user does on the computer -- word processing, web browsing, music, digital photography -- and all of those needs are served quite well on the Mac platform right now.
In the enterprise, sure, everybody does word processing, web browsing, etc., but beyond that, all bets are off. When I worked in a banking environment, I supported dozens of business-critical Windows apps, from third-party market data software to nasty, internally-hacked-together VB apps. Abandoning those apps wasn't even close to being an option. Even all the web apps in that environment worked only in IE on Windows. Any other enterprise of significant size is almost guaranteed to have dozens of critical apps of its own. I suppose if you really wanted to get a Mac into such an environment, you could access the Windows apps over Citrix or something, but that'd be a pain.
Even if app support wasn't an issue, most enterprises are already quite tied into the Microsoft stack -- Active Directory, Exchange, SharePoint -- which makes supporting Macs even as a secondary platform challenging at best.
And even if you consider that surmountable, it's still no wonder that Apple is more interested in home users -- they are (if you'll pardon the expression) the low-hanging fruit.
Maybe the reason is that the enterprise market is downstream. They're not the trendsetters. If you get all the individual users using Macs, eventually big cos will have to switch. Just as happened with desktop computers, in fact.
So maybe Apple ignores this market because they know they'll get it automatically (but only when) they're the default for individual users.
Easy answer. When they allow OS X to run on regular x86 hardware. Unfortunately they seem to think they're tied to the hardware business when their software is really impressive.
Apple seems to enjoy a reputation of making stuff that "just works." They are probably not prepared to guarantee that OS X will "just work" on anything but Apple hardware, and don't want to risk damaging that reputation.
If it's based on FreeBSD then I'm am very sure that there are drivers for most, if not all, of the hardware that a typical PC user runs. If not, the Linux drivers shouldn't be a complete pain in the ass to port?
I suspect you're right, but the issue is not how much of a pain they would be to port, it's how much of a pain they would be to support and what would happen to the typical end-user experience.
For example, I've never not been able to install Linux or Windows on an x86 machine, assuming the hardware actually works, but it's rare when two installations on different sets of hardware turn out exactly the same. An obvious example would be on windows, go to Control Panel:Display:Settings:Advanced and you get a whole bunch of options that are specific to your actual video card and monitor. A less obvious example would be an intermittently crashing program, because there is a bug related to memory addressing in the firmware of the motherboard.
The result is less consistency in the use of a Windows or Linux machine. By sticking with their own hardware, Apple can better establish a reputation for consistently satisfying their target audience.
"To the extent that Apple products have actually infiltrated big businesses, it's been through small groups of enthusiasts--the canonical example being the art department that somehow manages to get themselves Macs"
It's not just the art department anymore, it's now the software engineering department now too. (I'm talking large 10,000+ employee corporations.) This is mainly due to OS X's BSD upbringing. Deployment and general development on Windows is just a bitch when your production servers are nix based. Besides why have a Windows box when Macs themselves can run both Windows and MS Office easily (not to mention IWork is now a viable alternative).
In the enterprise, sure, everybody does word processing, web browsing, etc., but beyond that, all bets are off. When I worked in a banking environment, I supported dozens of business-critical Windows apps, from third-party market data software to nasty, internally-hacked-together VB apps. Abandoning those apps wasn't even close to being an option. Even all the web apps in that environment worked only in IE on Windows. Any other enterprise of significant size is almost guaranteed to have dozens of critical apps of its own. I suppose if you really wanted to get a Mac into such an environment, you could access the Windows apps over Citrix or something, but that'd be a pain.
Even if app support wasn't an issue, most enterprises are already quite tied into the Microsoft stack -- Active Directory, Exchange, SharePoint -- which makes supporting Macs even as a secondary platform challenging at best.
And even if you consider that surmountable, it's still no wonder that Apple is more interested in home users -- they are (if you'll pardon the expression) the low-hanging fruit.