The virtual - following Bergson and Deleuze - must not be seen as something non-existant, or even 'less real' - but an exteriority within the actual, an Outside, as the author coins it. In thinking of what the virtual is, we must investigate spatiality, perhaps we are forced to redefine it itself in light of virtual spaces. This is in part what Grossz sets out to do.
Grossz takes what is arguably a Deleuzian-Bergsonian-'Feminist Deconstruction' approach to critiquing the mainstream notion of Space and Time, to quite a fruitful harvest. The popular conception of VR is not a neutral space, an exterior with an unlimited amount of becomings. The notion of virtual space itself, for Grossz, has entered into popular consciousness in a male-dominated form, particularly in hedonist visions of potential futures.
Third paragraph, but I have yet to mention architecture, which this book seems to promise a great deal about. What gives? Well, Grossz is not an architect, nor does she claim to synthesize them; she explores the 'in-between,' like Plato's Chora in conception. She doesn't seek to 'force' elements from each onto each other, but simply point out some mutual flows and intensities.
The way she does this is how she explores the notion of Space; by exploring how virtual space has reconfigured the meaning of Space as we know it, architects can look at how they can rethink architecture. A room is constructed for the common activities that occur in it, by constructing a space for a different purpose, such as for bodies or better, by analyzing these activities and searching for a more creative layout, architecture can draw from the virtual.
Her architectural 'suggestions' are a little wanting, especially considering the Introduction seems to hype that up as an important polemic, however - this book is a highly engaging Deleuzean analysis of Space and Time, bodies, all that good late 90's/2000's structuralist stuff.