iPhone firmware update 3.1.3 available now

The iPhone OS gets an update today, via an iTunes update – it's not totally mind-blowing, but according to the changelog, improved accuracy for the 3GS battery meter, third-party app launch crash fix, and resolving of some bugs with the Japanese Kana keyboard are in store for iPhone users.

We've heard reports that this new update possibly will mess up your jailbreak from blackra1n and others, so users may want to wait out this one, until we get a heads-up.