The technique is pretty simple but gives great results. I have my camera set up on a tripod with a remote, and Pocketwizards connecting the camera to the flash in my hand. I walk around popping off the flash in areas that I think need it, usually to highlight certain features or bring up shadows where necessary. Try to make it believable - for instance, there wouldn't be light on the roof. Since I've been working at this technique for a long time now, I pretty much know what flash settings to use depending on the environmental conditions, e.g. ambient light, what color the house is, what type of surface I'm lighting, and so on. Usually I use a gel to give it a little more believability. After I'm happy with what I've lit (lots of chimping - in my case I shoot tethered so I can see the results up close) I mask them all together in Photoshop using layer masks. This takes some trial and error, but after a few attempts it's not that hard to get the hang of. After that it's a matter of sky replacement, curves adjustments, and color balancing. In some cases I will wait around until it's completely dark out and take an exposure of the inside light without any reflections for masking in later.
This compositing is a common technique in upper end Architectural photography. It probably doesn't make sense to spend time doing this for shoots of low end properties. This is the same technique that Andy Frame describes in the post we did on his shot of the motor 281' motor yacht Cakewalk. Mike's tutorial video gives some insight into exactly how this technique works. Thanks Mike!