If you upgraded from 5.0.1 to 5.1 you are probably finding yourself trying to downgrade or without a jailbreak.
Famous jailbreaker pod2g is currently working on finding exploits to develop the next most awaited jailbreak.
Even though this is only the beginning, is good to know the jailbreak of the new iOS is being developed.
Keep on reading EPELTECH more more jailbreak news!