http://www.zdnet.com/blog/security/google-cloud-print-pondering-the-security-privacy-implications/6461

Quoting the article:
"....
there are some privacy and security implications that need to be fleshed out before end users rush to submit print jobs to Google’s cloud.

The service, which is now being baked in Google’s labs and will be featured in the company’s Chrome OS, uses a cloud service to submit and manage print jobs."