Dreimos has let us know that the USA v1.51 "Security" Update is now available for download as was its Japanese counterpart a short time ago. Those interested in examining the release can do by grabbing it directly from HERE, however, we do NOT recommend anyone update to v1.51 yet. Based on the description alone "A patch has been added to address a security vulnerability in the system software" it appears this update is intended only to give those seeking LEGAL homebrew PSP possibilities via exploits unnecessary grief unfortunately. Those interested can discuss the news further in THIS Forum thread.