iOS 5.1.1 is out now. While it's mostly usability upgrades and bug fixes, you may as well upgrade if you can. As usual, the Redsn0w jailbreak tool is ready pretty much simultaneously, and Redmond Pie has a walkthrough for how to install it.
Specifically, this is the tethered jailbreak for all A4 powered devices, like the original iPad and the iPhone 4. It does not include the iPad 2, the current iPad, or the iPhone 4S. Like all tethered jailbreaks, you'll have to boot your device into tethered mode every time you restart. If that sounds like a huge pain, maybe hold off for the untethered release, which will hit in the coming days or weeks.
For newer devices, you'll have to wait. The hardware defect in the A4 devices means that the crack can come literally minutes after jailbreak devs get their hands on a new iOS update. But finding a way into the newer iPads and iPhones is a lot tougher and more time consuming. [RedmondPie]