To me this (leasing 1 *million* sq ft of new office space) signals that Google will continue to expand into new areas well beyond their core competence of search software.
According to the article, Google is sitting on $7 billion of cash, so they have the financial clout to try out new ventures and see which ones have wings.
The NASA Ames research park is marketed as the research center for nanotechnology, supercomputing, astrobiology and satellite design, so perhaps some of the new ventures will touch nanotechnology or perhaps astrobiology in relation to supercomputing?
Now, that's a bit farfetched to me, but as a kid who had to take the day of sick from school whenenver any Mercury mission was being launched -- in order to watch it on television -- I've just got to love the possibilities. This is in every great book by every great Sci-Fi writer in to 50s and 60s.