Attention iPhone and iPod Touch users: iPhone OS 3.0 is now available and ready for an update-filled adventure. Just connect your device, load up iTunes (version 8.2 required), and check for updates. It should download, unpack, and install.
Once you get it up and running, be sure to let us know what you think of the new OS and your favorite new feature. I'm excited for Apple's Universal Push system, which will increase connectivity for supported apps by notifying you of any pending messages or updates.
You can check out Apple's list of features here.