These brilliant cameras use 802.11b for wireless hook-up. They have their own web server, and thus do not need a PC once they have been hooked up. When set up properly, the camera can be access from anywhere in the world that has an internet connection, and can also be pan & tilted remotely.
Once it has been configured (by serial port), you just plug the camera into the mains anyhere within radio range of your wireless access point, and it attaches itself and is available. It can of course be used one-to-one (ad-hoc mode) to send its output directly to a wifi card equiped PC.
Video resolution is up to 640x480, and there is also a built-in mic, so you can hear whats going on too. I don't know of any retailer in the UK selling these.
Price is £239.99 including insured next day delivery.