Erica Sadun has a post over on TUAW explaining the correct pronunciation of "Mac OS X" (it's "mac oh ess ten", not "mac oh ess ex"). Some folks in the comments are not finding themselves able to deal with this.
Yes, Apple is being inconsistent: "Xcode", for example, is pronounced "ex code". And when you see that big "X" there you just want to say "ex". I totally understand. But I also agree with one commenter that there are people who will pronounce it wrong just to annoy. It's like Republicans who refer to the "Democrat party". It's petty and sad, but the best thing is to ignore it.
Anyway, I wonder if Apple missed an opportunity here. If they'd gone with the "ex" pronunciation, the name of their OS would have ended with "sex". They'd have thousands, maybe millions of people saying "sex" every day when referring to their products. Wouldn't that have been perfect subliminal advertising?
On the other hand, there are very good reasons why I am not in marketing.