[avarun]

...He's clearly talking about third-party replacements for the default messaging app, ie. apps that are allowed to interface with the SMS/MMS protocol implemented by your phone. Android has had this capability forever.

Not sure why everybody responding to him is being obtuse. If you don't understand something, maybe take a minute to think about it instead of assuming the person you're talking to is an idiot. (Not you, yours is the sanest response by far)