In my opinion, Facebook is no more trustworthy than Google when it comes to data privacy.
The difference is that if you are a typical Google user you've plopped a sea of data onto their servers that makes FB look tame by comparison.
Look at all the data that Google users store on Google's servers...do you really want to create a public profile for all the world to see that is linked to the following?
* Google Docs
* Gmail (imagine all the email sitting in your inbox, sent folder, the trash)
* Checkout (your purchase history if you used a Google shopping cart, linked to your credit card)
* Contacts (usually combine personal and professional)
* Social connections ("direct" and "secondary")
* Phone calls (if you use Google Voice)
* Photos (Picasa web albums)
* Blog, website, site analytics
* Web search history
* Chrome sync (if you use Chrome and sync your passwords)
* Google reader - the stuff you read
* Google group membership
* YouTube (your favorites, your comments)
* Google Buzz
* Google Mobile
Of course we're all going to use Google+.
All I'm saying is, use it smartly.
If you want to de-link your personal data from your public profile, create a dummy account that does not house the kind of data your personal/regular Google account houses.