@Embd SW netwk: No the *documents* are copyright. Using the documents to produce a compliant implementation is not breach of the document copyright. Purchasing the document alone *is* purchasing a licence to implement a compliant product. Copyright and patent are not the same thing, though they both deal with intellectual property. One is about original content, the other about original invention.
The google android site features a detailed video by it's engineer on what constitues the Dalvik VM and how it is different from JVM. I suppose google to have taken all necessary precautions to this effect.
Stack-based VMs have been around for a long time.
For example, the UCSD Pascal suite of the 1970's used a VM called p-code and there were numerous other examples.
Having worked on both p-code and JVMs, I struggle to see that the JVM has any huge leaps of invention past p-code beyond the addition of exception handling and garbage collection - features apparent in other VMs such as some LISP systems and postscript.
Ultimately the opinions of an engineer have no bearing on the matter. All that matters is the legal position.
As for the Dalvik VM, there is a very valid technical purpose for such a thing. It is not just some attempt to wiggle off a legal hook. Dalvik can be implemented more efficiently than JVM on many architectures.