I am wondering can I setup my windows phone 7(nokia lumia 800) with Google Contacts?
It's simply a case of going to: Settings -> email + accounts, and then adding a Google account.
You can then choose to synchronise Email, Contacts and Calendar (or any combination)
As posted in this link there is an application on the market called 'gsync' that can actually do the needful. Just search on the Windows Phone store, its compatible on WP7 as well as WP8..