Here's an article about someone who has a Sony PSP set to control his electrical appliances.
http://psphacks.blogspot.com/2005/04...ontrol-10.html

There is some debate about the authenticity of the article, however if it's the real deal, should be easily acheivable via a Tablet with WiFi and the right hardware.

I've tried some of the Smartphone IR software that does remote emulation, while it does work, the ultra short range makes it practically useless. I'd imagine the IR transmitter on notebooks would be no more powerful than those found on phones.