We knew this one was coming since the AOSP sources were pushed, and Jean-Baptiste Queru again made it official on the Android Building mailing list. The Linux kernel sources for the Crespo (Samsung Nexus S), the Stingray (Motorola Xoom), and the Tuna (Samsung Galaxy Nexus) are now in the AOSP manifest, with a handy set of links to sync just the sources for those not interested in the full Android source.
While Android controls the look, feel and features of a device, the kernel controls the mind. It's where some serious (and seriously cool) work can be done, and Android is full of the right kind of geek to do them. If you're any sort of hacker or flashaholic, and use a GNex, Xoom, or Nexus S, you're in luck.
Source: Android Building