I've noticed people building their own sensing power supplies, or trying to find where to get one.
If you are in the USA, a really good one can be found at
www.dalco.com. Search for part #69457. (~17$US)
If you are in Canada, their supplier can be found at ww.annasys.com. Same part number. (~25$CDN)
Here's the item description:
SURGE STRIP BASIC 7 OUTLET
Auto power-on/shut-down with the computer plugged into the first outlet (MAIN), all equipment connected on the same power strip will be automatically turned on or off by powering up or shutting down the computer.