While the list of tweaks is absurdly small in the latest iPhone OS update, we know that some of you simply have to run the latest and greatest OS at all times regardless of risk. Fortunately for you, the Dev-Team has stepped to with a new version of PwnageTool
(v3.1.5 for Mac OS X) that handles the update to iPhone OS 3.1.3
with aplomb while preserving your device's ultrasn0w unlock and jailbroken state. As usual, there's a litany of precautions depending upon the device you own so hit the source link and read the dev-team's words carefully before proceeding. With a little luck, patience, and undue stress, improved accuracy of your device's reported battery level can be yours -- Huzzah?