How does GPS-Segment Matching like Strava Work?

I'm not a cyclist, but some colleagues of mine showed me Strava today.

Basically they upload data from their GPS device from their ride in the morning and Strava manages to match the GPS data to known "segments" in their database.

These segments all have amusing names and with their GPS data some interesting Gamification occurs; who has the fastest time for that segment for the day etc.

I was wondering if anybody knew any algorithms or approaches that can be used to perform this sort of comparison. From Strava's engineering blog they have a lot of data available to them, so whatever algorithm they are using must be pretty fast. They also mention that some segments are manually created, but some are extracted from the raw GPS data.

Thanks!