EFI, it's the main difference between macs and pc's atm and it's bigger than one may suspect, the BIOS is a 20 something year old POS held together with hacks, my macbooks boot time is legendary even when booting windows, i just hit the button press down to select XP and bam the windows logo appears, none of this scrolling black text shit, no bios random issues, everything just works perfectly and reliably, it's pretty similar to open firmware, just a little less open.
I've switch many many more people to platforms other than windows through the soft sell, telling people they are an idiot for buying a pc from asda (uk version of walmart) is not going to get them to trust you to install ubuntu on it, you need to be open and talk to them about their needs and skills and determine what's best for them, this whole linux/mac/windows fanboyism that is so rampant with nerds needs to stop, otherwise people will just baulk at it and continue to use windows which we ALL don't want.
OS X is very much the user friendly version of unix, i'm skilled at useing linux/BSD and i run it on my headless boxen but everything i can do in linux i can do better/faster in OS X, unless i want to be completely customizing my OS linux is not really suitable for the desktop as OS X eclipses it in most respects, sure for those on a strict budget linux is still a good OS choice if your technically competent. but OS X is perfect for 90% of users and it has a complete open source underpinning.
It is imperative that linux is kept going, and i cant see anything killing it in the near to distant future in the server space, OS X will take a decent amount of that market from both linux and Microsoft once apple becomes more established, xserves are awesome 1U servers and are gaining marketshare fast once admins actually look at them.
OS X is not the end all OS, but it seems like the majority of linux geeks have been handed a near godly OS and they've shunned it because the UI and a few API's are proprietary, it's not perfect and it's not going to replace linux but it's a damn good OS inbetween windows and linux as it has allot of the advantages of both, apple is not going to become Microsoft, and if they did they would have to turn OS X 100% proprietary which would alienate most of their user base, being hostile to apple is completely silly.