A month ago Google announced that the Nexus One will not get Android 4.0 Ice Cream Sandwich. Since then we’ve seen only an SDK port running on the Nexus One, but now we’ve got an AOSP Custom ROM for it, too!
Here’s some more info, AOSP is the Android Open Source Project, the place where you “can find the information and source code you need to build an Android-compatible device.”
Just a week ago Google released the Android Ice Cream Sandwich source code to the AOSP.
In that time we now have AOSP-based custom ROMs for the following smartphones:
They’re faster and reportedly more stable than ROMs based on the SDK, and will only get better with time.