According to Apple Insider, the upcoming OS by Apple - Mac OS X Snow Leopard, will be location-aware just as the iPhone. It will use WiFi networks to triangulate the position of the user to allow geo-tagging and other location based services like updating the twitter location.
Apple Insider says: People familiar with the latest pre-release distributions of the next-gen OS say the software now includes the CoreLocation framework previously available via the iPhone SDK, which will allow Mac applications to identify the current latitude and longitude of the Macs on which they’re running. Since Macs don’t include GPS technology like the iPhone 3G, CoreLocation will utilize a Mac’s existing networking hardware to triangulate the system’s location in a manner similar to the way the original iPhone was able to use the technology to emulate a true global positioning signal.