...isn't really much of a secret. In fact, it's beautiful because it's about the only way to solve that problem given the particular constraints (and something anyone who's taken linear algebra will immediately understand). Google's particular implementation of that algorithm isn't any more useful than, say, RSA's particular implementation of public key encryption. I would much prefer they release something infrastructural (eg, the distributed filesystem) rather than algorithmic.
"A Note on the Eigenvalues of the Google Matrix"
http://arxiv.org/abs/math.RA/0401177
Interview with Matt Wells (GigaBlast)
http://www.acmqueue.com/modules.php?name=Content&p a=showpage&pid=135&page=1
Slashdot Mirror
...and of course, I refer to the 'Princess' series. Warning--most definitely not work safe.
"A Note on the Eigenvalues of the Google Matrix"
http://arxiv.org/abs/math.RA/0401177
Interview with Matt Wells (GigaBlast)p a=showpage&pid=135&page=1
http://www.acmqueue.com/modules.php?name=Content&