In a Google+ post yesterday, the CyanogenMod team announced that Ice Cream Sandwich (CM9) and Jelly Bean (CM10) won’t be supported for Snapdragon S1 devices. One such phone is the Nexus One and they stated that it would require a custom hboot to repartition the internal memory. The fact that there is only 512MB of RAM certainly doesn’t help the matter. On top of that, compromises to the CyanogenMod code would be necessary because of the proprietary libs available from 2.3.
They went on to say that “with enough time, effort, and hacks” it could be made to work, but they don’t feel the experience is worth all of that. Other main attraction phones that have the Snapdragon S1 are the HTC EVO 4G and the HTC Desire.