Today iH8sn0w released the new sn0wbreeze 2.8 beta 2, the program still works using the exploit limera1n and custom ipswâ€™s can be made only in Windows using sn0wbreeze. Mac OS X users may like to use Redsn0w 0.9.8 jailbreak which is available for both Windows and Mac. Redsn0w is currently tethered for all supported devices.
You can check which bootrom version you have, using the program F0recast and if he tells you that you have new bootrom than your jailbreak will be tethered and not untethered.
Download Sn0wbreeze v.2.8 for developers