Which perks?

Vacation? No
Health insurance? No
Free cell phone? No

Free food? Yes (but might be restricted to certain cafes)
Gym Access? Maybe (depends on what kind of contractor you are)

Google's a huge organization. Coming up with a one size fits all description would be impossible. For instance, the contractors in India have very different access than if you're a SWE contractor in mountain view. And of course, for book search, the people who were paid to turn pages for the scanner don't have access to buildings outside of where they're supposed to be, so it's definitely not at the same level as an employee.