BTW (Citace z iFans):
"iOSx2 is an interesting work-in-progress project started by iFans forum member pEAcEmAKeR that allows for you to dual boot multiple versions of iOS on your device. Before following through with the project, it’s important to understand that there is a significant risk that you can permanently damage your device, even with considerable knowledge about modifications and tweaks. I would recommend giving this handy FAQ a read before following the dual-booting tutorial.
The project currently supports the iPod touch 1G, iPod touch 2G (MB model), and iPhone 3G running a firmware version between 3.0 and 4.0.2, but the contributors (namely Hexane and jsp20) are working on expanding the project to the iPod touch 3G, iPhone 4, and iPad 2. There’s also an official iOSx2 application that will allegedly be released on Cydia by next year. For updates on the project, there is an iOSx2 portal along with an official Twitter page.
We’re working on an app that installs iOSx2 on your device automatically, similar to iDroid’s Bootlace, and will also allow easier booting between iOSs. That’s what the icon up there is for. It’ll be hosted on Cydia. The best ETA we can come up for will be sometime during Summer or Fall 2012."
Oficiální web projektu:
http://iosx2.org/tvosi: Musím souhlasit ale stále je dost developerů kteří chtějí udělat aplikaci pro novější iOS a čistý

Prostě se nemusíš bát, že ze svého hlavního systému pomocí špatně nakódované aplikace smažou třeba kontakty
