The Dev-Team has managed to jailbreak iOS 6 beta 3. It’s a tethered jailbreak, and it’s intended only for developers of jailbreak apps, so that they may test things out.
Others should stay far away from it. The good news, however, is that it is possible to jailbreak the software, which is a good indication that things should be working well when it releases to the public this fall.
Here’s their latest update:
“Update #2 – July 16: The “dev3” version covers today’s 6.0beta3 release (and also adds explicit support for 6.0beta2). Please point redsn0w at the 6.0b3 IPSW in order to jailbreak beta3 and boot tethered. ** You must use “Select IPSW” to point redsn0w at the beta3 IPSW before every tethered “Just boot” **”
You can read more about their progress on their official blog: Dev-Team Blog