3Jam, mentioned previously, which provides 'Reply-All' functionality for text messages. Unfortunately, it is significantly clunkier than some of the offerings from yesteryear (eg Group Messaging from Vodafone Ireland and Orange UK from circa 2002).
Here are some of the commands:
Looks like lots of hard work to me!
- Add a friend to your 3jam address book: add john brown 14123423534.
- To send the first text message along with the 3jam initiation, include a dot (.) after the 'text' command and then type your message: text John Kyle Jane . Hey guys what up?