So, what happened? Since the Verizon Galaxy Nexus was the first missing device spotted, folks immediately thought it was furor over the Google Wallet issue on that device. In fact, Google made a statement to The Verge implying that, but later backed off, saying it had made that statement in error.
Instead, it appears to be a technical issue. As Google's Dan Morril explained on a Google Groups page, CDMA devices are being removed from the AOSP site because they need carrier-signed .apk files (which users can’t generate). In other words, they can't be open source, and thus can't be part of the AOSP.
This includes Sprint as well as Verizon, and would include other CDMA carriers, such as U.S. Cellular, as well.
Still, this change does give AT&T a potential for a slight PR edge over Verizon, now. Both have LTE service, with Verizon's far more widespread across America, but since Verizon uses CDMA as a backup, in a way, it's somewhat of a second-class citizen when compared to an AT&T LTE device (not really, but hey, we're talking about marketing here).