my buddy made an oaked elderberry stout. 16oz dried elderberries in the primary. dry hopped with 8oz elderflowers. it came out great a stout can handle and hide the elderberries alot, having never had mead i have no reference there. with the right malt(or honey) profile i think elderberries are great. I would however cover that tree asap as the birds love em and you will have none left if you are not careful.
Sounds like I have something to do tomorrow morning, then! And sounds like I'll have something interesting to add to the graff I plan on brewing on Wednesday.