The CyanogenMod Team has been working hard on CM10, and have shared a status update. Previously we reported that the CM team felt it would not be hard to move to CM10 with Jelly Bean because there are not very many differences between Ice Cream Sandwich and Jelly Bean. Apparently, their suspicions were true, as their post suggests that we will get the CM10 Jelly Bean build pretty quickly. Here's a quote with their full Google Plus post:

Jelly Bean Status Update

Repositories for all AOSP projects have been created on our github to alleviate any potential mismatches (branch is 'jellybean').

While Jelly Bean won't require a major rewrite of all the CM features, the source has been re-arranged and re-factored enough that a simple merge isn't possible. So we will proceed with manual merging (this was to be expected really).

The plan of attack will be to cherry-pick everything from CM9 and fix the merge conflicts and relocations. Itís tedious but the only way. Ideally the original patch authors will forward-port their changes, so if you are out there and want to help out, join us in #cyanogenmod -dev.

+ Trebuchet might be messy to rebase onto JB.
+ Theme Engine will be messy.
+ SystemUI stuff will need to be restyled.
+ Lockscreen stuff will need to be restyled.
+ The current UX of Settings is good, no reason to change anything there.

A manifest (Cyanogenmod/android.git) will be going up later this afternoon, so the masses will be able to sync directly from our source at that point as well.

This will be it on the updates (so we can focus on actually working). Next post referencing JB should be when the merge/cherry-pick process is complete.

-CyanogenMod Team
That's pretty exciting news! I wonder how all the other developers in the wild are doing?

Thanks for the tip, Darla!

Source: Google+ - CyanogenMod Team