<p>While I’m skeptical of the generalizability of the conclusions drawn by both of Gladwell’s books (I think his main point, notwithstanding, is not that we should trust our intuitions ALL the time [EDIT: oh, wait, I just read Blink, different from Tipping Point :p], but that they’re sometimes more trustworthy than a lot of people currently think), the “rule of 150” is one of the more rigorously supported results in his books (and yes, I have heard of it from multiple sources prior to reading it). It also happens to be one of the most generalizable of his points (since most humans are more or less homogeneous in this respect). I just cited his book since it is perhaps the book through which the theory is most widely known.</p>