The usage of apostrophes in the plurals of initializations or acronyms is debatable. Technically it would be correct to pluralize the abbreviation without the apostrophe, but "our society has become ... accepting [of] a more and more vulgar form of English" and now tends to accept the apostrophe-plural as the norm.
The pot, my friend, is black, as is the kettle. (Edit 2: Aw, shit. I'm drunk. Upon re-reading this thread, I realized that you,
RichieB, are not
Mac Donald. Damn. Okay, so the pot isn't black. My apologies. But the following point still stands, except for the from-your-viewpoint comment. Heh. Oops.
Since this has stood for almost a half hour, I'll keep it since you might have read it in its original form, and I want you to see my apology.)
If I were you, I'd be chasing after the you'res and yours of this internet world, as well as the other many grammatical missteps. But arguing about the pluralization of apostrophes is an exercise in futility, especially from your viewpoint. eeek.
Edit: I would agree that this would be best referenced in only the prior thread, especially if you're only citing something this pedantic... particularly if there's already been several posts there.