I bought Them and first read it before 2001-09-11; those events certainly put a different complexion on the chapters about Islamic extremists. From various other sources, I had already heard of the Bilderberg Group and had no doubt it existed. The only question — now, as then — is what kind of power it projects. I suspect quite a lot, actually.

(Another group that definitely exists and of which I'm somewhat suspicious is SMOM, but last time I looked their membership fee was a "nominal" $50,000 per annum, plus character references from two senior Catholic clergy. I'm not sure he could reailstically have infiltrated that one…)