No. But if you're in standby the machine is not shutdown. If there is a power failure you can set the bios up to automatically power the machine back up depending on your bios. I'm not sure how windows would react to scheduled events passing before the scheduling process starts, but I think it can. Not to useful for TV recording.
You'd need a DAMN good reason to need to turn a machine off from a 'powered off' state on schedual to want to do such a project, can't think of any reasons myself, if you have one though go for it, wouldn't be too hard, the power button on a PC is nothing more than a basic logic switch nowdays, VERY easy to interface to a 5V external logic.