That means if you bought your device before today, or before Apple patches the hole in manufacturing, you may be able to jailbreak your device without Apple being able to do much - if anything - about it.
Any day now expect the iPhone Dev Team and others to publish software that will make it simple for anyone to jailbreak their iPhone or Touch.
It seems serendipitous that the jailbreakable vulnerability was announced on the same day Apple made its iOS 4.1 upgrade available. As Paul McDougall points out, the upgrade offers a number of enhancements including a social gaming platform, TV show rentals, iTunes Ping, advanced photographic capabilities, and fixes a number of bugs and other performance issues.
However, users may want to think twice before jailbreaking their devices. In February, Apple filed for a patent that covers the ability to spot and disable various unauthorized uses of an iPhone, Touch, or iPad - jailbreaking included.
So by jailbreaking the device, you may not only be voiding the warranty - but you may one day end up with a bricked phone or MP3 player.