Just a FYI. There is a free new app called LeafSnap for iPhones & Androids that enables you to take a photo of a tree leaf and it will identify it for you. As of now, there are only 184 species but I tried it yesterday and it worked perfectly on a Sweet Gum. Now, if they would just enlarge the number of species and add flowers, it would be fantastic. Just thought I'd share.
Handy New Tree ID App
I take that back; the Android app is not yet done, but it is in the works.
That sounds interesting! I have a Droid, so I'll have to wait.