[Kiro]

Just because you haven't seen this many articles about WhatsApp before doesn't mean they haven't been closely inspected before.

[Helianthus]

This article is from March 2012. It has been posted twice before to HN to little impact.

http://hn.algolia.com/#!/story/forever/prefix/0/Whatsapp%20s...

(Correction: the presentation is from 2012; I don't know when it was posted online.)

[saurik]

https://news.ycombinator.com/item?id=3028547