If you already have an iPhone the upgrade is free. If you have an iPod touch or
even iPad, it's going to cost $9.95. All you simply do is connect to iTunes and it
picks up the update and asks if you would like to install it.
Remember that the full capablities of OS 4.0 will only be able to be used on
the 3GS and the next gen iPhone which will be announced in June.