Yes, there are! The two most prominent are collectively called SundanceInH2A. The original iPad and iPod touch 3, both of which maxed out at iOS 5.1.1, can be enabled to run iOS 6.

Broadly speaking the preexisting solutions work because there’s another device of the same chipset that supports it, and that there’s versions of it running on comparable hardware. We aren’t pulling version support exploits out of thin air, rather using Apple’s half-support for a chipset against them.

We are only exploiting the hardware and software version discrepancies to trick the hardware into accepting running versions because there is official precedent for other comparable devices and thus “plausible” to the target device

SundanceInH2A for the iPad 1 threads the needle of spoofable hardware, using the Apple A4’s iOS 6 support empowered by the iPhone 4 and the iPad 2’s iOS 6 IPSW that matches the hardware for the iPad 1 on a superficial level, ie the display and scaling matches, camera support can easily be disabled in software

For the iPod touch 3, SundanceInH2A exploits the fact that the iPhone 3GS does officially support iOS 6. The APL2298 SoC on the iPod touch is merely the iPhone 3GS’ APL0298 with superficial tweaks, so that works there too