The base OS, libraries, and functionality is GPL, but Google's apps (gmail, maps, youtube, gtalk) are not, as was made clear with the the alternative android in

The base OS, libraries, and functionality is GPL, but Google's apps (gmail, maps, youtube, gtalk) are not, as was made clear with the the alternative android install that included a copy of these apps. Also, I suspect there is some kind of revenue sharing agrement with the use of these apps, so carriers that provide the google branded apps get a cut of related search revenue. This could help keep licensees in line and discourage things like forks or going it on their own with the pure GPL version.