There’s a critique of Google’s new Desktop Search that it…wait for it…searches your computer! No, really, it does. And so it finds things that are … on your computer! Some of these things, like your email, your spouse’s email, your IM logs, are things that Microsoft hides intra-user are exposed. This is probably a bad thing, but they were exposed before, but not placed on your desktop for easy access.
There’s a related complaint, which is that Google picks up confidential documents that webmasters expose to the internet, and lets you search for them.
There are other concerns that are more legitimate. Google should segment Gmail and Orkut from the main searches. Google could sell you an ad-free Gmail account. That would be cool. But I can’t see why anyone would be upset that their email is being indexed, unless data from that index is sent to the mothership.