The implications of #3 are interesting.

Having an UI that allows you to perform most actions within 1 or 2 clicks is a tremendous UX/UI challenge...

Of the five tips, #3 is the only one that speaks to me.

Taking these growth hacks one by one:

1. Users hate insta follow but it's successfully addresses the "cold start" problem.

2. Staggered Facebook friend follow is evil and might be against the Facebook terms of service, but it's very effective: "When you sign up for Pinterest with Facebook, your friends who are already using Pinterest auto-follow you and you follow them back. But all this auto following doesnât seem to happen all at once but is staggered over time so that you get periodic notifications that someone has just started following you on PInterest."

3. Any action anywhere is great for keeping people in the feed view: "I can perform almost every action that I would take anywhere on the site all from within my feed, including: commenting, liking, re-pinning a post, following a friend."

4. I'm not a fan of infinite scroll. The "click for more" button of 9gag and Tumblr seems just as effective.

5. Less than 1% of Pinterest users use the bookmarklet. I'm not convinced that bookmarklets are a normal user feature, but I sure do like the PandaWhale bookmarklet.