Hi Easty,
If you're serious about setting up a "low key" GPS comp for Tassie sailors, can I suggest you form a new team within the GPS TC and run it exactly the way you suggest, with people posting just their top speed as shown on the display and noting where they were sailing and what type of board they were using (hmmm, this is starting to sound a lot like what 550 people around Australia are already doing within the GPS TC

). Anyway, ... this would probably be a lot easier to coordinate. Also, for those who start to get hooked on the GPS thing and want to see how their true speed (2 sec) compares to other sailors around the nation, how far they sailed and how well they gybe, etc then it's just a matter of them posting their uploaded data (which is no more difficult than uploading photos to facebook).
An even better suggestion would be for you to all join the Tassie Speed Seekers!!!! We want you all on our team!!!! Serious plug: It is a heap of fun regardless what gear you are sailing or what level your sailing is at.
Anyway, back to the topic, Easty, you could be the official person to collate the data every now and again to select the reigning champ on different boards at each of the different locations and post it on this forum.