As it turns out, the dolphin-uplift origin story IS NOT set in the Uplift milieu! It has been incorporated into Brin's next novel,
Existence. Which is set in a different, less space-opera universe.
Another chunk of the book, the novella
Seasteading, is available online in a few places.
Brin has a blog / discussion group where he might answer questions more speedily than the mailing list:
http://www.davidbrin.blogspot.com/
GURPS Uplift was more work than my master's thesis and didn't make me a millionaire.