Kraftwurx Chat system can chat with each other while on the move.

Login to Kraftwurx.com and then:

iPhone Web-app
http://www.kraftwurx.com/cometchat/iphone

iPad Web-app
http://www.kraftwurx.com.com/cometchat/iphone

BlackBerry Web-app
http://www.kraftwurx.com/cometchat/bb