I have SEVERAL wild cherry trees along my back property line.
I have a couple questions.

1)  If I had desirable cherry scion, would the graft be compatible?
2)  If the answer to #1 is yes, does anyone have any great cherry scion they would be willing to share for postage or trade?

The short answer is maybe...
It depsnds on what you mean by wild cherry and if you want pie or sweet cherry. Here is some more info:

http://www.backwoodshome.com/articles2/clay121.html
http://forums2.gardenweb.com/forums/load/fruit/msg112118541799.html

If you do decide to graft onto your trees (one way to find out if it will work is to try), PM me and I can help with some scion.

Greg,

I have grafted Northstar (dwarf sour cherry) to a native. I beleive is native Black cherry, and to seedlings of some Ornamental weeping cherry which I imagine was Yoshino. I actually posted in that gardenweb thread linked above