lubricus writes "Facebook announced plans to acquire WhatsApp for four billion cash, plus 12 billion in Facebook shares.
Additionally, WhatsApp employees and founders will receive three billion in restricted stock which will vest in four years. Facebook also agreed to a one billion dollar break up fee.
WhatsApp says they have message volume which approaches the global SMS volume, and hope to have one billion users. Even at those figures, Facebook is paying $16 per user.
I'm guessing WhatsApp will send Snapchat developers a cake."
could be an alternative:- forward secrecy- does not store contact lists on the server, apparently only cashes hashes of your contacts for a period.
Business model? unknownSource code? unavailable
surely Facebook 'cashes' while Threema 'caches'