One interesting sideshow tied to Moneyball's publication is the vociferous negative reaction to it by baseball insiders with thin skins. This rhetoric took place at the same time that the actions of baseball insiders were correcting the mis-pricing!
But I don't believe that the actual publication of the book altered prices so much. Rather, when other teams raided the A's front office for talent, those guys, and others who had figured out what was going on, did the bidding. What motivated Lewis to write had also motivated teams to copy the A's, and that occurred (shortly) before the book hit the stores.
Now, as for EE's comment (#3 below Dave's post). This comment, (echoed by Rod & Dave) poses the big question that Jahn Hakes and I left unanswered. Let me re-phrase it: how long was a winning strategy lying dormant? If indeed it was dormant for decades, and obvious enough to alt.rec.baseball types, and as cheap as the A's found it, why? It is not enough to say that the people running sports teams are stupid, or ignorant, or lack computational skill. Branch Rickey was not stupid, and as EE says, he and his people knew the importance of on-base percentage a long time ago.