Why we don't sell ads (2012) https://blog.whatsapp.com/245/Why-we-dont-sell-ads ?
I think the story blew out of proportion. As far as I can tell, WhatsApp never said they would show ads in their app, and they never said they would sell ads. On the contrary, they said that they would make it even harder for them to have any data to work with, as messages will be end-to-end encrypted, and so, undecipherable for them. What they said would happen was telephone and metadata (ie, telephone contacts) cro…
From their update ( https://www.whatsapp.com/legal/#key-updates )
"New ways to use WhatsApp. We will explore ways for you and businesses to communicate with each other using WhatsApp, such as through order, transaction, and appointment information, delivery and shipping notifications, product and service updates,
>>and marketing.For example, you may receive flight status information for upcoming travel, a receipt for something you purchased, or a notification when a delivery will be made.
>>Messages you may receive containing marketing could include an offer for something that might interest you.We do not want you to have a spammy experience; as with all of your messages, you can manage these communications, and we will honor the choices you make."
I interpret the highlighted parts to mean they intend to show ads in the application in some format. It could be ad overlays, it could be adbots sending messages and it could be ad notifications.
Edits: figuring out how to highlight text :X