LOL...trust me, I'm nowhere near their caliber.
Not even close. Besides, I doubt that privilege is yours to give.
Because if this works, it will be a relatively new phenomenon. SHSH signing was introduced by Apple with the 3GS. The 3GS didn't ever really have a "once pwned, always pwned" exploit that existed for it over the course of its production life with an easy point of injection (24kpwn is in early-bootrom 3GSes, but redsn0w relied upon the USB security hole that existed in iOS 3.0's iBoot to get exploitative code into the system...as I recall, you didn't have to DFU to install a custom IPSW on 3GS), unlike iPhone and iPhone 3G which had the DFU-based "Pwnage" exploit. limera1n is more like Pwnage than 24kpwn, is my understanding.
While I was typing this out, though, I had a short Twitter convo with MuscleNerd, and it turns out that we were both kind of right.
You can do what I suspected you can do: downgrade to 4.1 using custom IPSW + limera1n exploit, without SHSH hashes for 4.1. However, the SHSHs are still needed...for it to be UNtethered. You can apparently downgrade to 4.1 without SHSHs, but it will be tethered boot only, much like the current 4.2.1 jailbreak. So for those that want to downgrade to 4.1 and don't have SHSHs, I guess there's really not much point.
(For limera1n-based 'sploits, the untethering bit is apparently handled after SHSHs have been checked by the OS, so as of limera1n-based versions of PwnageTool, the custom IPSWs apparently DO cause iTunes to go out and collect hashes, which is different from the way it was before.)
http://twitter.com/MuscleNerd/status/19906571546927104
http://twitter.com/MuscleNerd/status/19912981357797376
-- Nathan