Race rules have changed, even in the relatively short time we have been running in Alaska. Many races no longer allow personal or outside GPS trackers, whether or not the race organization provides their own during the race. Here are a few resources you can check if you're still trying to get up-to-the-minute GPS tracking.
Iditarod: subscribe to an Iditarod Insider service featuring GPS.
Many mid-distance races also include GPS tracking, often for free. Some to check out:
Copper Basin 300 GPS Tracking
Kuskokwim 300 GPS Tracking
Tustumena 200 is often available on TrackLeaders.
Denali Doubles is also planning to work with TrackLeaders. Check here for updates.