I believe that no patents were filed at Sun on Self technology through
to the official end of the project in '95.
More recent implementation ideas, particularly ones originated for, or
used in JVMs, are likely to be patented.
I doubt that any were filed while it was a Stanford project, but even
if they were, they're probably expired now, or close to expired (17
Caveat: I am not a lawyer, and no facts were checked in the creation
of this response.