Apple already approving apps with iOS 4.3 specific features
Apple has approved an update to an app that required iOS 4.3 for all the features to work correctly. The app that has received the approved update is called StreamToMe. StreamToMe is an app that allows you to stream music, photos and videos from your Mac or PC over WiFi and 3G. Nothing special there except that this version has the option to use AirPlay which requires iOS 4.3 to function.
Apple seems to be in a hurry to get iOS 4.3 out of the door. The normal two week updates have been reduced to every week for this beta so expect to see iOS 4.3 sooner rather than later. As with all beta's however major bugs can be found so this could all fizzle out and delay the whole process; it does however look like iOS 4.3 could be just around the corner.