The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Nic Jackson:
Designed for adventure runners, ultra marathon runners or just about anyone who wants to track their location whilst out and about. Adventure Tracker is designed to run in the background and update your location to the server every 10 minutes. Adventure Tracker can update your position for up to 20 hours with a single battery charge.Data is automatically uploaded to the Adventure Tracker website where you can view your tracks or send tracking links to friends. If you are in an area where there is no mobile reception such as out in the woods or in a foreign country Adventure tracker caches all the data it is unable to send to the server so you can upload it over WIFI or 3G when available.The Adventure tracker website allows your followers to view your tracks with your position updated every 10 minutes, create track links and export as GPX format which is a common file format used by most GPS devices). New features are coming daily, soon you can manage all your tracks, tweet your position and download any trails as KML file format.Example Track (21km run):http://bit.ly/b4tBWFDue to multitasking requirements this application requires iPhone OS 5.0 and iPhone 3GS or iPhone 4.Please Note:Continued use of GPS running in the background can dramatically decrease battery life.