Apple today released the latest build of their iOS 4.3 beta to developers. This is beta number 3 (8F5166b). We don't know much about it at this point, but as always we will be keeping an eye out for anything new that comes from this latest developer version of iOS.
We recently wrote up a list of new features found in iOS 4.3 (with one added earlier today) and you can see that here. We are sure that the list will grow as time goes on, but for now feel free to keep track of major changes by checking out that list. We will update (both the list and the blog) as we get more info on the upcoming release.
As always, developers can head to Apple's website for the update. The rest will have to wait. As we've mentioned before, it's not a good idea to try to trick Apple and download the update as they seem to keep tabs on iDevices with UIDs registered to developers.: Here