The news comes as O2 – the iPhone's first operator in the UK – is now allowing handset owners to tether their iPhones free of charge via USB or Bluetooth, as well as offer complete in-contract unlocking, Infosecurity notes.
According the 9to5Mac news wire, the 4.3.3 jailbreak works on a Mac or a Windows computer and the jailbreak even adds a multitasking gesture facility not normally seen on the iPhone.
It's important to note that the ultrasn0w jailbreak only works with selected basebands on the iPhone, but this compatibility can be checked fairly easily.
"The iOS 4.3.3 untethered jailbreak is based on the exploit created by @i0nic for iOS 4.3.1", says the news wire.
As new jailbreaks for the iPhone are appearing very quickly after an iOS update, O2 seems to have woken up to the fact and is now offering contract users the ability to unlock their handsets from the O2 network by filling in an online form.
The process then takes 14 days and requires connection to iTunes, but it does allow users to legitimately unlatch their handsets from the O2 network.
In addition, in parallel with a revamping of O2's data bundles, the cellco is now offering 'free' tethering via Bluetooth and USB connection, although Infosecurity notes that the data usage will come from users' data bundles, and does not work across WiFi connections.