Yep, that’s what pcworld is reporting anyway, the Apple iPhone and Apple iPod Touch is to gain a Yahoo! Messenger application.
With Yahoo! Messenger installed on the Apple iPhone, iPhoners will gain all the usual chatting and communication gear associated with a mobile messenger, and if you don’t hold a Yahoo! Account then you can sign up for one direct from the iPhone.
Furthermore Yahoo! Messenger will stay active while you make a call or switch to another application, however there is a time limit of ten minutes of inactivity. The iPhoner will be able to send SMS messages from Yahoo Messenger for the iPhone to either IM or iPhone contacts.