In a post to the Android Building group earlier today, Jean-Baptiste Queru announced that Samsung's Nexus S 4G has officially and fully been brought into the AOSP fold. The device is now fully supported by AOSP, meaning its CDMA – and WiMax – binaries can now be "properly" distributed. Here's the full text of the announcement:

We've been able to resolve the issues around Nexus S 4G, and we can now properly distribute its CDMA and WiMAX binaries. That allows Nexus S 4G to work with AOSP just as well as Nexus S.
As a result, we now consider Nexus S 4G to be fully supported in AOSP, with no restrictions. Overall, Nexus S is the preferred platform for AOSP work.
I've updated the set of IMM76L binaries for Nexus S 4G to include WiMAX support. They're available at their usual location:

Some readers may be wondering why this is a big deal. Back in February, there was a bit of a scare that the CDMA Galaxy Nexus would be dropped from Google support. This brought to light a general issue between CDMA devices and open AOSP support caused by the fact that (according to Dan Morrill) "recent CDMA Android devices" rely on proprietary code from carriers, a lack of which means "pure AOSP builds running on these devices can't place calls, access mobile data, and so on." In essence, Google was unable to provide truly full "support" for the devices, since it could not provide full code. The Nexus S 4G, however, is now fully supported, with the Android team evidently having ironed out legal wrinkles surrounding the device and its relationship with AOSP.

For those interested, the Nexus S 4G's factory images can be found at Google's Developer site here. In a post to Google+, JBQ explains "this is meant to be used by people who built and flashed their own custom version of AOSP and wish to return to the factory state." Others, he goes on to explain, should simply wait for the OTA (the arrival date of which is unknown).

With the Nexus "back in AOSP's good graces," CyanogenMod (on Google+) rightly notes that we can only hope to see the CDMA variants of Samsung's Galaxy Nexus get a "similar treatment."

Source: Android Building Group Via Google+ (1, 2)