fwiw - Some information about the UUID and the not yet released uuid package in the commons sandbox. Of course a device wide mutex in java would make most of the work around the various strategies available in that package obsolete, but I don't know how to do that eloquently. http://jakarta.apache.org/commons/sandbox/id/uuid.html and the IETF spec: http://www.ietf.org/internet-drafts/draft-mealling-uuid-urn-05.txt (including link here since I just realized the docs in commons-id need the updated url.)
Thanks, -TR
