Google Latitude works by installing components on your desktop or notebook computer, or on a smart phone. It uses GPS and known Wi-Fi hotspots to determine your location, then displays them to friends who are also using the service. They'll be able to see where you on are a map.

As you can imagine, there are huge privacy and safety implications here. Fortunately, you can control just how much specific users get to see, letting some friends know right where you are. Others see a general city location or nothing at all.

Of course, the Google Maps app also does what you'd expect, giving you excellent location-based searching and directions. I wish it did voice-recognition, as does Windows Live Search Mobile.