This is a guest post from CNET News Senior Editor Donald Bell, who covers portable entertainment from tablets to MP3 players. He's also a musician, a hardware hacker, and a collector of vintage audio gadgetry. He appears every week on CNET's Crave video podcast.
Bell put together this easy-to-follow gallery tutorial for those who may be new to updating firmware. The free iOS 4 upgrade is available today for both iPhone and iPod Touch users, but does not include first-generation models.
From the gallery:Step 1: Upgrade iTunes
To upgrade your iPhone or iPod Touch to Apple's iOS 4 firmware, make sure you're running the latest version of iTunes on your computer. Here's a link to iTunes 9.2 from CNET's Download.com. After installation, you may need to restart your computer.
Once you've made sure iTunes is up to date, connect your iPhone or iPod Touch to your computer using the included USB cable. If iTunes doesn't launch automatically, you'll need to launch it manually.
Once iTunes is open, and your device is connected, select your device in the iTunes sidebar so that the summary page (shown here) is visible. Take notice of the button for Check for Update but don't click it quite yet.
Just to be safe, make a backup of your settings prior to upgrading the firmware. To do this, right-click on the device icon in the iTunes sidebar and select Back Up. It should only take a minute to create a backup, and it's time well-spent. If anything goes awry during your iOS update, you can use this same menu to select the Restore from Backup option.
Finally, click the Check for Update button from the device summary page. If your iPhone or iPod Touch is compatible with iOS 4, iTunes will tell you that an update is available for download and will guide you through the installation.Bytes and pieces from an iOS walkthrough" (ZDNet)