I just photographed this tree, about 10' tall, in Brooklyn, New York...It is a tree, but seems to have been trained into this form. The leaves appear viburnum-like, the flowers richly scented. Googling led me to Viburnum farreri. Can anyone confirm this?
Perhaps more likely its hybrid Viburnum × bodnantense 'Dawn' (V. farreri × V. grandiflorum) - a very popular garden shrub.