Apple website in the US is not displaying yet when the latest update to iOS 4.0 will be released.
However, Apple website in the UK says that iOS 4.1 software will be available for download on September 8. The iOS 4.1 software update is the first major update to iOS 4.0, bringing Game Center, new iTunes features, photography features, and etc.
Another source revealed a download link for iOS 4.1 firmware for unreleased iPod Touch 4G. If you’ve just put your order for the new iToy, you might want to download a fresh copy of iOS 4.1. File size is approximately 580.2 MB. You can get it here.
Update: Sept. 8, 2010
iOS 4.1 is now available for download.