From Android we only use the kernel, and system tools and low-level libraries; no Dalvic/Java infrastructure, not even all of the daemons. For porting to new devices, we need a handful of files from the previously installed Android system, such as binary drivers and device-specific config files. The rest is completely build from source. So we are fairly independent from Google's release cycle, as long as we support any version of Android for the device.
