The first Apple's iPhone software update is automatically available to iPhone users when they connect up their iPhone to iTunes via their PC or Mac. The iPhone patches are believed to mainly address security issues and fix software bugs. The patch addresses some Safari vulnerability issues, according to reports from early iPhone updaters, but version 1.0.1 doesn't activate any additional "hidden" iPhone applications that some iPhone users have speculated about .
According to a report on TUAW (The Unofficial Apple Weblog), the software update wipes any unofficial iPhone modifications off the device. Other than that, there don't appear to be any major iPhone software updates.