Looks like iOS 4.3 Beta is now available for download in the iOS Developer Center along with some pre-release Apple TV software. We'll be taking a look and letting you know what's new since the last beta shortly. [Apple]
Bah, so frustrating.
I have waited to upgrade to 4.2.1 so I could get a non-beta untethered jailbreak, and now I might as well wait for a proper 4.3 jailbreak.
I have been in fear that my iPhone will get stolen before I can activate the Find My iPhone feature in 4.2.1.