The wait is over. Apple just launched the new iPhone 3.0 Software update. The new iPhone OS, available for free for current iPhone users, offers over 100 new Features. iPod touch users once again have to pay $9.99 for the new iPhone Software Update.
You can download it now via the latest iTunes release.

To get the iPhone 3.0 firmware update onto your iPhone you need to follow these 4 steps:
1) Make sure you are using iTunes 8. Connect your iPhone to your computer.
2) When iTunes opens, select your iPhone under Devices in the Source List on the left.
3) In the iPhone Summary pane, click Check for Update.
4) Click Download and Install. Do not disconnect your iPhone until the update has finished.



More Details:
iPhone 3.0 Software Update for iPhone page
iPhone 3.0 Software Update for iPod touch page.