As per usual, the latest greatest major iPhone OS release will precede the release of the new iPhone model. The iPhone 4 will be available June 24, and iOS 4 will be available on June 21. Guess what iPod Touch owners? It's free for you too, as it always has been for iPhone owners.
You know the drill, plug your iphone into your computer and fire up iTunes on the appointed day to get the update. We're sure Apple's servers will be busy, so patience grasshopper.
iOS 4 is compatible with the iPhone 3G, iPhone 3GS and the iPod Touch (except the first gen iPod Touch).