I checked out the link you provided even though I was a bit dubious.
I stopped reading when I reached number 6. By 'mobile phone' I presumed the author was speaking of a cellular phone since he took pains to be clear that this would not work with cordless phones.
Anyone who has such a slippery grasp on the way that cellular phones actually work has to be lying through his teeth when he says he cooked an egg in this fashion.
I really don't know enough about the technology to really say one way or another, although it left me a little skeptical as well.
About the only thing that might do it is some sort of harmonic electromagnetic "feedback" between the two transmitting phones, similar to what happens in a microwave oven.
But then again, I doubt that the average cell phone puts out sufficient power to do anything like that.
I did a search on SNOPES to see if they had anything in their hoax & urban myth database on it - they don't, so I emailed the link to them.
This is just the sort of thing that can go crazy on the internet / e-mail (remember the "exploding microwaved coffee" warning that went around a couple of years ago?) so they might want to be on top of it.
If any FReepers are crazy enough to try it, please report your findings back to us, won't ya?