Usually when a new iOS version is out, it takes quite a while before the hackers are able to perform untethered jailbreak on it, but a special case for iOS 5.1 do happened. i0n1c, one of the hacker had posted a tweet saying that he already had iOS 5.1 untethered jailbroken on his new iPad on the day of release.
Later on, he uploaded a video on YouTube showing that he actually do have his new iPad untethered jailbroken. It's just a matter of time of when the exploits will be updated to reflect this finding. I guess it won't be that long in the future.
I believe this might be a good news for those who wanted to buy the new iPad since they can expect to have the devices to be untethered jailbroken when they arrived later on. In the past, people had to wait for quite a long time before they can perform a fully untethered jailbreak on their devices, leaving them with tethered jailbreak for those who can't stand using the official version.
Here's a video from i0n1c uploaded on YouTube: