to google, or not to google

..is it Bad Manners to Google a person? Is it an invasion of their privacy or a reasonable thing to do in getting to know a person?

I've only Googled people I knew well, usually when they are there (always seems like a good thing to do after a few glasses....) and its always interesting. I'm sometimes tempted to Google people as I'm fairly nosy at heart (and me a blogger? amazing)....