"Oops I'm Late!" is an American notification application for Windows Mobile phones based on GPS.
Whether you are late, on time, or early, "Oops I'm Late!" keeps in touch on your behalf.
Designed primarly for busy business types, who might not be able to call ahead to advise of tardy arrivals because they're driving, it seems quite simple to use.
Once you've bought the app (prices are from $69.99) you just enter your appointment information in your calendar as you would normally, either on your phone, desktop or web.
Turn on your phone's in-built GPS, then open "Oops I'm late!" on your phone.
The program will connect to the Internet in an attempt to geocode your information using geonames.org.
You then add attendees from your late/arrival notification and "forget about it".
Head off on your business, where ever you need to go, when the late status has been determined by the settings you provided, your contacts will be notified accordingly.
If you're State-side, then check out the 3-day free offer on the site below if not, then hope for an international roll out.