What might these be?
Appears to be a member of the Nightshade Family (Solanum).
Can't tell for sure, but may be Solanum dulcamara, an Introduced species. (see link below).
Here is a link that might be useful: Bittersweet
Thanks for the potential ID. I have that variety of nightshade everywhere in the yard. I don't recall any of them ever turning blue.
Is this a tree or a shrub? Are the leaves arranged alternately or opposite one another on the branch? It's not quite clear from the picture.
Black Haw, Viburnum prunifolium, a great shrub for wildlife. When ripe the black fruit is soft and sweet.
I think Sam may be onto it. That would mean the leaves are opposite. Viburnum rufidulum is only possibility. In my area, the leaves of V. prunifolium have a matte finish, the ones in this picture are a bit lustrous, more like V. rufidulum for me. The leaves buds in winter (actually forming now) should help distinguish between the two.
Thank you very much! I walked back to find the berries again a few days ago, and I am having some difficulty locating they again.