The trick is that Google doesn’t claim that Android is a Java platform, although it can run some programs written with the Java language and against some derived version of the Java class library. Sun could prevent this if they had a patent on the standard class library, but they don’t and, even if they did, I strongly doubt it would be enforceable since Android doesn’t claim to be compatible (and in fact, could very well claim that their subset/superset is an innovation on the existing patent and challenge Sun’s position).
sucks to be sun right about now. they should have listened to the ASF.