Hmm, we don't seem to have the original message anywhere ...
In any event, the usual ways of getting a plane down from a tree include :
1) climb the tree
2) throw things at the plane
3) hook a string around the plane and pull
4) cut down the tree (or part of it anyways.)
5) wait for the wind to dislodge it
6) use a long pole to push the plane free. (Home Depot sells telescoping poles up to 30' that work nicely. You can also duct tape long PVC pipes together to get a longer one, though after a while it becomes very hard to work with.)
7) use a ladder
Sometimes using various combinations of these methods will work :)
If you get really stuck, you can often call a tree maintenance company and they can come out with a big ladder and get your plane down. Often with much less damage than other methods may cause, though they don't usually do it for free.
You might be able to talk the fire department into doing it, but of course there's the danger that they'll be tied up when there's a real emergency. (And hopefully they won't let you talk them into it if there's such a risk.) They may justify it as a training opportunity, or by removing it themselves, they remove the risk that a kid will climb up and try to recover the plane himself and get hurt.
I've heard of somebody whacking a plane down from power lines by hitting it with an electric Zagi. I don't suggest this, however, unless you want two planes up there ...