Apple has released the new iTunes 9.2 Beta to support the new iOS 4 and iPhone 4. This beta version is only testing purpose and for Mac users only (sorry Windows now available for windows too). The final and public version will be released at the time when the public iOS 4 is available i.e., June 21.
If you want to upgrade your iPhone 3G or iPod touch to iOS 4 before the final release, you will need two things: iTunes 9.2 Beta and iOS 4.
We have already shared the download links for iOS 4, and here are download links for iTunes.
iTunes 9.2 Beta, 69.62MB
Other Versions of iTunes: