Pinterest Growth Hacks: How did it grow so fast?

There's a lot regarding Pinterest's growth on Quora. For starters, see<p>"Which viral concepts is Pinterest getting right that may be enabling their staggering growth?" <a href="http://www.quora.com/Pinterest/Which-viral-concepts-is-Pinterest-getting-right-that-may-be-enabling-their-staggering-growth" rel="nofollow">http://www.quora.com/Pinterest/Which-viral-concepts-is-Pinte...</a><p>and "Why did it take so long for Pinterest to go viral?" <a href="http://www.quora.com/Pinterest/Why-did-it-take-so-long-for-Pinterest-to-go-viral" rel="nofollow">http://www.quora.com/Pinterest/Why-did-it-take-so-long-for-P...</a>

Hmm, the #2 Facebook Auto-Follow hack is interesting.<p>I wonder if any users had a friend follow them, then mention it to them in person and have the other person be like "Oh...I never followed you."

I'm skeptical that the bookmarklet was a major driver in Pinterest's growth. My wife was an early and avid Pinterest user and fairly tech savvy (though not a hacker). She had no clue about the bookmarklet–or what one is–until I showed her recently.<p>Thats anecdotal but I suspect accurate(unless you have data to prove otherwise).