As with almost any software update, Apple has introduced new issues while ironing out a couple of others. As I said before iPhone is far from being the on-board companion you'd like it to be as rSAP (wireless bluetooth connection for your car) simply isn't there. Automotive forums around the web are ablaze with talk that iOS 4.1 has introduced any number of playback problems, with the bulk of complainers citing scratching, crackling or random disconnects when piping audio from their device to their vehicle via the dock connector. Prior firmwares have caused permanent incompatibilities between our iPods and vehicles before but that's not a surprise since the dock connector doesn't respect proper USB standards and not even the 3GS was able to properly handle AVRCP(remote control profile for wireless headsets).
I know it's impossible for the software engineers at Cupertino to test antenna designs, battery designs, security holes and apparently everything else for that matter, so probably it's time to completely cut all corners and hire a dev team from China, the closer to Shenzhen, Foxconn where iPhone is made, the better. It really makes no sense to pay developers that couldn't seem to grasp the concept of a mobile OS for almost four years now and even less of how the device is made.