If you wanted to block access of a single machine to all sites whose domain is owned or controlled by Google, how would you go about generating a comprehensive list to add to /etc/hosts? How would you handle Google Apps sites?
Maybe a better solution would be to lookup the IP classes owned (registered) by Google and blacklist (deny) them in a firewall (iptables).
To get the IP classes owned by Google, you could start by gathering IP addresses from different classes (maybe using DNS to resolve different well-known Google domains) and using one of the many online WHOIS services (an example) which indicate how much of that class (the subnet mask) is owned by Google.
Just a side note: getting the IP classes is not quite practical and probably not the only way. Not sure if you can find them somewhere already published...