Mike recently wrote Space-Age Tech Coming to a Building Near You: Aerogel as Insulation It is true that it hasn't been used much as conventional insulation in solid walls, but because it is translucent, it has been used a lot in applications where architects want natural light and a high level of insulation. Kalwall puts Cabot's nanogel aerogel between two layers of fiberglass panels and gets R-20 out of a translucent wall, which is certainly not passivhaus standard but is five times that of a modern high efficiency window. Kleinfeldt Mychajlowycz Architects used a lot of it on their FESTI Building to enclose the stair towers.
Kieran Timberlake Associates
Kieran Timberlake Associates used it on their stunning Yale University Sculpture Building and Gallery, as part of an elaborate wall system:
To maintain a predominantly transparent envelope, without compromising the building's high level of energy performance, a curtainwall of triple glazing and insulating translucent spandrel panels has been combined with an exterior sunshading system to reduce solar heat gain in the interior.
As Mike suggests, Aerogels might replace conventional insulations in buildings. But the real revolution will come when buildings are designed to take advantage of all of their attributes, providing insulation and natural light at the same time.