It depends what you mean by 'enabled'. Obviously, the laptop has to have the relevant hardware and software installed but it can't really be said to be fully enabled unless a fee has been paid for the service. (There are a few free wi-fi hotspots around, particularly in places like libraries, but you usually have to pay a subscription first). This can cover a month at a time or just be for a quarter of an hour's use. See here for prices:
http://www.zdnet.co.uk/specials/wifimap/operat ors-pricing.htm
As long as there's a subscription in place (or there's a free hotspot) then basically, as you suggest, it's just a case of 'turn-on & log-on'.
Chris