Hey all- the company I work for released a new version of our iPhone GPS topo map product, AccuTerra, and it's now a free download with one map download included. Grab a Rec Area (National Forests and other public lands) or a National Park product for the best detail - nearly the entire state of Colorado is a National Forest anyway. Those categories have much better detail than the the State maps.
The maps are normally $3 to $5, so a 'first map free' promotion is a fairly good deal. It will also track in Google, so you don't have to buy anything to use it as a dirtbag GPS.
We're also going to have all North American ski areas (runs by difficulty, lifts, lodges, etc) in a few weeks, so you could hold off until Vail or which ever area you ski is available. Those should be approved by Apple by Jan 1st. Here's a shot of Vail:
itunes page: iTunes Store
Just trying to get the word out to my outdoor brethren who have iPhones.