Garett Rogers had this blog about "Google's secret IPv6 plans". It appears that Google owns a block of IPv6 addresses numbering approximately 7.9 x 10 28 (79 billion billion billion addresses) or 2 96 . Basically Google owns any IPv6 address from:

2001:4860:0000:0000:0000:0000:0000:0000

to

2001:4860:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF

ARIN (the organization that allocates IP addresses on the Internet) only gives IP blocks of this size to ISP for the purpose of reselling to end users and companies. Put this in the context of Google's continued purchase of dark fiber (unused fiber optic cabling, much of it left from the dotcom era) and the construction of a massive data center, it's clear that Google is trying to position itself in the heart of the Internet.