I admit that to me, OS X adoption of 10% seems slow at first.
But when I stopped and think about the life cycle of a typical Macintosh, it is not unusual. My mother used her Macintosh II for 10 years and that is not unusual. She typically bought two (or more) PCs in the same time frame as her mac purchases. I know more people whose latest Mac is a Revision A or Revision B iMac than I know who have a G4. And the questions I've seen people ask at the MicroCenter store within a store stump me: Can they use this archaeic Epson printer with OS X, or what SCSI (!) scanners do they carry. Glad I don't work there. All indicators that the Mac world repleat with people who haven't upgraded their peripherals to USB and Firewire, let alone their OS to OS 9 or OS X.
Everyone talks about the amazing Return On Investment and mean time between upgrades of the Macintosh. The 10% just shows that this hasn't changed. It also shows what an amazing OS OSX is that it can get such a large percentage in only a year. Those of us who remember the switch the PowerPC know what I mean.