If it's for the arrival of a female, you don't need an app. Just add 25mins to the time they told you they'd arrive.
Didn't the Palm Pre once advertise this feature? As in if you had an appointment in your calendar tied to a GPS location, your phone would tell you that you're running late and it would send an email/SMS to the person you're meeting with to let them know. I also believe it was supposed to route you the most efficient way to hopefully get you to your destination on time.
It never came to light?