An iPhone developer, John Heaton had discovered hints of iMessage iOS code which contains traces of iChat feature which might be possible start of integration between iPhone, iPad, iPod and Mac. iChat currently allows you to connect with famous chat messenger e.g. AIM, Gtalk, Jabber etc will also support iMessage capabilities.
If the functionality is built in to iOS then you would be able to send messages to your friends directly onto their desktops and vice versa using internet connection. Apple considers close integration of devices strong edge over rest of the devices available which are apparently clear for FaceTime feature which is available across the board for iPhone, iPad, iPod Touch, iMac and Macbook Pro. We would love to see the concept materialize in order to increase Apple devices bonding and making communication even more easy.
iMessage feature was introduced in iOS 5 released along with iPhone 4S which allowed sending of messages to other iPhone users over the internet connection for free. The concept is same as Blackberry Messenger which takes each device as unique identifier and allows free text communication.