Redsn0w 0.9.8b9 is a tethered jailbreak that works on just about any iOS device except for the iPad 2. It's not likely that an untethered jailbreak will be available soon since iOS 5 is still beta-ware, so you're going to need to plug your device into a Mac or PC running Redsn0w every time you power it up. Otherwise, it's not going to boot into a jailbroken condition and all of those unofficial apps will be worthless.
To jailbreak your device using Redsn0w, you'll want to be a jailbreak app developer who has a legitimate Apple developer account. You need a copy of the iOS 5 beta 5 firmware file and iTunes 10.5 Beta 5 as well. Don't even think about trying this jailbreak unless you have other skills in your toolkit, such as being able to switch your iOS device into DFU mode and restoring it with iTunes.
Potential jailbreakers should also remember that applying this jailbreak to your device will keep it from receiving OTA updates from Apple until you restore it to an original state. If you're still itchin' for a jailbreak, head on over to the Dev-Team Blog and download Redsn0w.