Not only has Apple released iTunes 9.2 to the masses, they seem to be approving and releasing apps updated for iOS 4 compatibility now as well. If you haven't checked your updates tab in a while, it may be time to tap that App Store icon on your iPhone or check in iTunes.
Out of my 100 or so apps I have installed on my 3GS, I've seen about 4 or so apps in the past 12 hours receive updates for iOS 4 compatibility. I'm assuming that number will only grow over the next couple of days as developers ready themselves for the release of iOS 4. Now that doesn't mean they have any iOS 4 specific features -- it just means they've been compiled with the iOS 4 SDK.
Some apps will have much more significant updates than others of course. So far I've seen updates for apps such as DropBox, Quota, Fandango, FlightTrack and a few others. Quota is touting the fact that it's supporting the higher resolution of the iPhone 4 in its update straight away. I'm curious to see which other developers will do this straight out of the gate. I hope most do as I can't wait to run higher resolution applications on my new iPhone 4!
Streaming music, navigation/location, or VoIP (voice over IP) app in the background are some of the big ones of course. Saving state for fast task switching is something we hope is also rolled out quickly and universally.
Hit the break for some screenshots of some I've found as well as a video from one of our readers demonstrating the in-app SMS feature Apple has given developers and API for. Thanks Ethan! Any of you find any apps that are running iSO 4 compatibility yet? Leave 'em in the comments!!