Apple says that tomorrow is the day for the new iPhone OS 3.0 but it seems that you can jump the gun a little bit according to Gizmodo!
While the update can't be found in iTunes yet, you can download it directly from Apple's servers. The download is available here. Be aware that it is a direct link to the IPSW restore image.
Gizmodo provided the following notes for those taking this route:
- To install this, you'll have to restore your iPhone to the downloaded firmware.
- The build number is the same a the Golden Master, which is to be expected. Likewise, the feature set should be the same.
- This will not work on iPod Touches, so don't bother trying
- The update will probably propagate through iTunes before too long