I remember his original article, and I think that for large organizations, it will take quite a while for Macs to really make it. Apple has a much better chance in small to midsize companies as long as the price/performance factor is right.
I'm going to be starting a small business towards the end of the year. The office will have both Macs and PCs, and I plan on running Mac OS X Server in order to avoid MS license fees. Long-term, there will be a mixture of OS X and Linux/BSD servers.