Under Options -> Location Based Services. You can turn it on or off. Yes, Blackberry Maps works fairly well. In Internet Explorer, if your device is tethered to your PC, clicking >>this link
<< will install Blackberry Maps to your device. There are other services available as well such as >>TeleNav
<< which will give you step by step directions via voice and also allows you to find businesses, cheapest gas in your area, etc. TeleNav costs approximately $10 per month.