Doesn't Google Talk qualify as the messaging app included by default? Not sure I see the droves of WhatsApp users migrating to that, sadly.
I want to send a message to people and they read and respond whenever they want. I want people to message me and I read and respond whenever I want.
I don’t want to deal with ping, hey, you are online why are you not responding. This is why half my Gtalk contacts are always “away” even if they are at the keyboard: presence status has become useless, let’s just get rid of it.
Presence makes almost no sense when the program implementing it resides on a phone, where any time someone sends you a message--even if the application isn't running--you'll know (because your pants just buzzed), and could very well react to it if you felt like it. You're always "present"; you're just sometimes purposefully non-responsive.
...now, on the other hand, "openness to being interrupted" status could be pretty useful. :)
I think what you want should be a setting in my machine (whether phone or computer): silence all notifications when I don’t want to be interrupted (I use iOS “Do Not Disturb” all the time).
Source:
http://www.whatsapp.com/faq/en/general/21864047
"We do not store your chat history on our servers. Chat messages are considered private and are only stored until they are delivered."