Seth Finkelstein has a thoughtful piece on Google and privacy in the Guardian, which includes this insight:
The lack of substantive knowledge about Google’s actions, combined with general concerns regarding how its logs could be abused, makes it difficult to sort out the real threats. For example, one of Google’s most well-known bloggers did student cooperative work at the US National Security Agency. But while this fact is a running joke in certain discussions of Google’s possible links to spying agencies, it’s ultimately meaningless. Any intelligence agency moles at Google (and it’s likely there are a few) will not have a public record identifying them as potential secret agents. However, without much concrete on which to focus, the substantive issue ends up only discussed in terms of symbolic factoids.
The task is then to prise out any abuses from behind the wall of corporate secrecy. Otherwise, we could end up with an unholy alliance between corporations and governments, where corporations act as privatised spies for governments, while government data retention mandates are used to give corporations an excuse to keep the sort of detailed records they’d want to in any case for market research and sale.
The amount of data Google collects on web users, combined with its expertise in indexing and data-mining, presents a danger worth addressing. There are similar dangers from other companies.
MichaelZimmer.org 
Again Seth is leading the charge. Do you trust Google with your data? Once they figure out how they can make money with it I’m sure they care to protect the info in a limited fashion. The fact that they use the data to make money is the reason why they securre the data.
First, Google’s entire business and technological model is based on capitalizing on user data. They need to track and map users’ actions across the web in order to “enhance their services” (as they put it), and they utilize these unique profiles of users’ needs and wants to target customized ads.
Second, this isn’t a matter of whether or not Google keeps the data “secure” – its about the very fact that they capture that data in the first place, and the fact that it is tied to IP addresses, cookies, and Google Accounts. Secure or not, the potential to turn such personal data over to 3rd parties has equal (if not more) danger than someone hacking in to steal the data.