iOS4 is now available to download. First, you'll have to get iTunes 9.2 though. This happens amongst the most chaotic phone ordering process yet. For those who were successful in putting orders for the iPhone 4 online, orders were randomly getting canceled even after payment details were accepted.
To get multi-tasking, folder organization, better mail and iBooks on your mobile phones, get iOS4 here.
For all you wanted to know about the new iPhone click here.