To me, a great case in point is the growing buzz around group texting apps. Group text apps such as GroupMe, Beluga and Disco allow users to form groups that can send and receive text messages in a sort of reply and read all manner.
You can think of it like group chat or reply all emails, but on the go and on a mobile device. You can also launch group conference calls from the service. (Right now most are limited to US carriers as sorting out International texting is going to prove trickier.)