Mary, that is a great question... Not only it's affect on home values, but it's impact on the surrounding area. The "New Urbanism" model is one that integrates community and becomes part of the 'fabric' of the existing character. Architecture and design are important as are transportation and pedestrian accessibility (and safety). Therefore, they are not built as 'gated-communities' nor neighborhoods that have one or two streets for ingress/egress (don't mean to offend anyone living over there in thos nice bungalows ;-) ). I'm sure the planned nature preserve and green-space will be open and availalbe to ALL, just like the park at Glenwood Park and how the street grid patterns were respected there also.
It will be a very nice development of homes, but they will not be 'comparable' homes to what most Kirkwood homes are, so they will certainly improve the quality of life for many Kirkwood neighbors, but I do not think it's going to have a huge impact on the surrounding older homes - though slight... that will be dictated by the current market, in my humble opinion.