Recently, Apple released beta 2 of the iPhone 3 firmware for developers. This brings many new features and overall performance improvements for iPhone. If you are not a developer but want to try out iPhone 3.0 firmware (although it is still in beta and care is advised), here are the links to download and install it.
Note: This article has been updated with iPhone OS 3.0 final version links.
iPhone 3.0 final download links
The iPhone 3.0 beta 2 is labeled and known as build 7A259. Different versions of the firmware are available for different versions of iPhone and iPod Touch, so pick the right download links for the iPhone 3 beta 2 firmware.
iPhone 3G
http://tinyurl.com/sizlopedia-iphone3g-direct-30
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iPhone 2G

http://tinyurl.com/sizlopedia-iphone2g-direct-30
iPod Touch 2G
iPod Touch 1G
The Megashare / Rapidshare URls to the firmware downloads have not been hyperlinked to the pages for obvious (legal) reasons – hope you will bear with us. The links above are for build 7A259.
The firmware is available in parts, so you should use a zip software like IZArc to download, extract and join the files.
To avoid waiting time for the downloads (which are at Rapidshare), you can use Skipscreen Firefox addon.