In addition to officially acknowledged security enhancements and a series of undocumented fixes/improvements, iPhone Update 1.0.1 also improves compatibility with a number of third-party accessories that exhibited issues under the initial software/firmware revision.

For instance, as part of our iPhone accessory compatibility index, we tagged the iRhythms A-302 incompatible, as it generates severe audio distortion even when the iPhone is in Airplane mode under software/firmware revision 1.0. However, after the update, the iPhone generates no discernable audio distortion when put in Airplane mode.

In addition, a report by Walt Mossberg on the All Things Digital site says:

“After I did the update, I was suddenly able to route the iPhone’s music output through my car iPod adapter, which the iPhone had previously recognized only as a charger, even though it acted as both a charger and an audio adapter for my iPod.”

Previous coverage:

• iPhone Update 1.0.1: Undocumented fixes, improvements galore: volume, stability, VPN, battery, more
• iPhone Update 1.0.1 troubleshooting: Problems installing (especially with hacks); more
• iPhone update 1.0.1 released: security fixes

 See more in http://www.iphoneatlas.com/