For those of you familiar with Google Latitude which has been around for a while now, it is a location service which you can use to display your current location as well as the location of your connections. Until yesterday there was not history available it just showed you where you were at any given time. Yesterday Google announced two enhancements to Latitude. Location History you need to go to your account and enable this feature if you want to use it, and history is private not public. Additionally at any time you can clear your history or clear specific entries from your history. 
Imagine that you’re Latitude friends with your roommate or co-workers. It would get pretty annoying to get a text message every single time you walked in the door at home or pulled into work. To avoid this, we decided to make Location Alerts smarter by requiring that you also enable Location History. Using your past location history, Location Alerts can recognize your regular, routine locations and not create alerts when you’re at places like home or work. Alerts will only be sent to you and any nearby friends when you’re either at an unusual place or at a routine place at an unusual time.
This is an interesting approach google took on location alerts, I wonder how good their algorithm is to figure out when to send the alerts actually is. You can enable your Location History and Alerts on the Google Latitude Apps Page. Google Latitude, now with Location History & Alerts