The new maps are in the rotation on servers 1, 2, 3 and 5.

Servers 4, and 6 do NOT have the new maps in the rotation at this time.

If you have not yet bought the map pack (First Strike) from Steam, you can still connect to 1, 3 or 5, but when the new maps come up in the rotation, you will be automatically kicked from the server.

and believe me, they do not come up often.