Viburnum opulus. Fruits are edible.

Wikipedia says its edible in small quantities but mildly toxic and can cause vomiting and diarrhea if enough is consumed.

First poster above is right, it's Highbush Cranberry, V. opulus or possibly the American Highbush Cranberry, V. trilobum. They're so similar that it takes a trained botanist to tell them apart, from what I've read, and I guess there is some debate in botany circles about whether or not they should be separate species. I've seen the American labeled V. opulus americanus by some sources.

Anyway, I've never heard of any consumption issues in terms of gastrointestinal upset. I suppose, like any fruit, overconsumption could cause issues. But, many of the companies that sell the more exotic edibles, like Raintree, One Green World, St. Lawrence Nursery, sell this plant. I think there may be a couple of improved strains out there with better flavor. And, it's sold very commonly in the trade as an ornamental. The variety 'Sterilis' is the 'Snowball Bush' which is a common spring-blooming landscape plant (and often confused with Hydrangeas, also called 'Snowball Bush.'

Um, I've picked these fruits before and made a jelly/jam type product with them. The ones you've pictured are NO WHERE near ripe or ready to pick == they really need to be 'bletted' by the frost before you pick them, it soften thems and makes them somewhat less astringent. However, this really isn't a fruit which you can eat raw anyway, it needs to be cooked to break down the rest of the tannins that make it astringent, and it needs to be sweetened to be palatable. Then, it's not bad, hence the name 'Highbush Cranberry' -- the end product tastes a lot like cranberry sauce. Here in Michigan, I would say the prime time for picking is early November, possibly as early as late October if we've had a couple of good frosts.

This plant likes damp locations, often growing on the margins of wetlands, but will grow in ordinary garden soil in cultivation, as long as it's not too dry and sandy. I could pick a bumper crop of these if I wished in the fall at a local park, where they used a big long row of probably 30 bushes of these as a windbreak/screen for a parking lot.

Thanks to ALL!