iOS 4.3 has only been available for about two weeks, having been originally released on March 9, just prior to the introduction of the iPad 2. While relatively few issues have been reported with the new OS version, BGR suggests that iOS 4.3.1 is expected to arrive in the next one to two weeks.
While this is expected to be a fairly small update, BGR says that it will provide baseband updates for the iPhone 3GS and iPad, fix a memory hang that results in memory corruption when reading large files from the USIM filesystem and resolve a problem with NTLM authentication on websites and in apps, plus fix an issue with the Springboard and with third-party apps not recognizing the gyroscope in the iPad 2.
Most importantly, the update is designed to patch an iPad 2 vulnerability that hackers used to jailbreak the device. Expect to see the software update coming soon via iTunes.