Apple's upcoming iPhone OS 3.0 has been leaked to torrent sites ahead of its official launch on June 17 - not surprisingly given that the so-called "golden master" (build 7a341) was just made available to developers. Jesus Diaz over at Gizmodo first reported the leak, which I verified on a couple of torrent sites, and went on to describe the fairly simple installation process.
This is the actual build used at WWDC'09 as well as the build Apple plans to distribute next week. The file weighs in at around about 230.1MB and takes around 45 minutes to install; covering the update process itself as well as restoring previous data, copying and updating applications, and transferring songs back to the device.
Gizmodo claims that the new operating system works without any glitches, bringing with it much-awaited features like landscape keyboard orientation in apps other than Safari, copy-and-paste functionality, push notifications, improved calendar support and more. Needless to say, as with any other unofficial release, download at your own risk, and remember to backup your device first just in case something goes wrong.