I never fully understood it either; in fact, you bringing it up reminds me to ask Pastor Riley!  One "possible" explanation is that in the KJV, the verse is translated:
 
And they answered and said unto him, Where, Lord? And he said unto them, Wheresoever the body is, thither will the eagles be gathered together.
 
Christians have, from time to time, been called "eagles" ("They will soar on wings like eagles..." in Isaiah 40, for instance), and I've heard it said that the word "body" in the original text was capitalized (as in Yahshua's "Body").  I will let you know what Pastor has to say on the subject.
 
Your sister in Yahshua!
Peggy
www.his-forever.com