Much like the iPad wifi, which was jailbroken within 24-hours of its April 3rd release, the iPad 3G was found to be just as eerily hackable as it's wifi brother.
Comex's Spirit jailbreak was shown in action by MuscleNerd almost a month ago on the first wave of iPad launches. By April 30th, the iPad 3G's launch, MuscleNerd was able to run the Spirit jailbreak with no troubles.
One thing about the JB is that it's most useful for Apple's newer iDevices such as the 3GS, the 3rd-gen iPod Touch and of course the iPads. The problem is that you must have a firmware version that doesn't close the vulnerabilities. It's always a good idea to back up your SHSH blobs with in order to keep those particular versions in case you should ever happen to accidentally upgrade (causing you to lose the ability to run the Spirit JB).