Landscape Urbanism sounds like a great name that really mesh together a lot of what I believe in and do as a professional. So much that I had considered a company name of “Olson Planning & Landscape Urbanism“, until I did some research about what is defined as “landscape urbanism.” According to Wikipedia (great source, right?): Landscape Urbanism is a theory of urbanism arguing that landscape, rather than architecture, is more capable of organizing the city and enhancing the urban experience.  I emphasized the portion of the definition above that I couldn’t get past.  
Although I feel that landscape and the work of landscape architects is critical in creating great places, there is no substitute for great urbanity defined by the structures.  There are instances that I have come across where the building, due to its initial intended use, do not allow some of the features of architecture to frame the street and give the vitality.  Using a lot of the principles of architecture, hopefully the landscape can create place-making and pedestrian experience.  Time will tell on its abilities to do so.
I do not feel that landscape is a fair substitute for good quality architecture but a tremendous companion.  As Landscape Urbanism continues to evolve, I hope that it is embraced by New Urbanism and the New Urbanist community as a compliment to new urbanism and a substitute only when necessary.  It has some very strong arguments, but can not be a substitute for quality architecture.  The two movements need to work together hand-in-hand.  Landscape Architects play a critical role in shaping our cities, however it is a difficult argument to say that landscape can enhance the urban experience better than architecture.