My guess is that "wiring" the house is one of the smaller technical and operational issues that you will encounter. You could look into wireless PTZ network cameras (at least 2 Japanese consumer electronics companies make reliable ones). The cameras can be controlled over your network through a web browser, or can be triggered by motion sensors.
Just make sure to encrypt your wireless LAN or your neighbors will be selling tickets :)
The camera streams (probably MJPEG or MPEG4) could be captured by a local server, and mixed, converted to whatever it is that you want your users to access (MMS, RTSP, or what have you). e.g. you set up 6 cameras strategically around your house, but only 2 streams are rebroadcasted to your hosting provider.
Videolan is an example of (open source) software that you could use to convert your streams.
As I said, wiring the place is the easiest part by far. Getting it to the server is a bit trickier, and getting it to the right (paying) users - even harder.
