"iBoot and bootrom are based on same code, and geohot says newer iBoots show his hole fixed (so next bootrom will be fixed too)". 

What is meant with this? Well, both iBoot and bootrom are based on the same code. Geohot found this vulnerability a while ago when both iBoot and bootrom contained the code that made them vulnerable. Likely, Apple noticed (by testing their own code) that iBoot and bootrom contained bad code. They fixed it in iBoot, but not in the bootrom (since it's read-only). Geohot noticed that the code was fixed in a later revisions of iBoot, so that hinted that the next bootrom (hardware) revision will contain the fix as well. iPad 2G and iPhone 5G will very likely not be vulnerable anymore for geohots bootrom exploit.

That's pretty much why he wants to release *his* tool now, instead of the SHAtter exploit, so that SHAtter can be used for the next iOS devices.

I hope this cleared things up.