220 outlets generally have different sockets and won't fit a 115 (standard) cord. (i should know. . . I spent the summer building infrared heaters . . some were 115 volt, some were 120 volt, and some were 230 volt (220 in europe))
anywho, try a different outlet.
It sounds like a bad outlet, you may have popped a breaker somewhere.
If different outlet doesn't work, you probably friend your power supply (what the other guy called power adapeter: the big box of transfromers in the corner, with all the power wires coming out of it on the inside)
If that is the case . . . go to
www.newegg.com and buy a new one. Antec PSU's are generally considered to be the best (cleaner power = longer system life)
or just send it to the apple people and the will fix it in return for a glowing customer testimonial.