First, I am not directly connected with any dev team and my information is only what "I" know and is my take of it. Please do not take my information as the end all be all of information. Just don't want people thinking the wrong thing.
With that said, both exploits are boot rom exploits and are supposed to be un-patchable unless the hardware itself is updated.
What does that mean?
It means that current hardware has certain boot rom and boot rom is not supposed to be remotely updateable or software upgradeable unless done at the factory. So, can they patch it? Yeah but only on new phones moving forward.
The down side? The boot rom exploit is tethered only.
What does that mean?
It means you can't power down / shut down your iphone without losing the jailbreak. You would have to wait till you can connect to a PC again to re-apply the jailbreak. Comex however wrote some code to allow this to be an untethered jailbreak. Both the Limera1n and Greenpois0n jailbreaks are using this soft patch to make them both work untethered.
So, what I see coming is Apple will release 4.2 but worst case scenario we will end up with a tethered jailbreak as they will most certainly patch the exploit used by Comex to make it untethered. (How often do you really need to fully power down your phone anyway? Resprings are not a concern.) Of course, I wouldn't be at all surprised if Comex and the gang already have a plan for that.
Like I said, that's MY take on it all. Someone please correct me if I am wrong.
Fred