What about on the Nightside?
That's one of those things that depends on factors I'm not entirely sure of. The zodiacal light (sunlight scattered by zodiacal dust) would intensify to the same degree that sunlight did, so if the Sun brightened enough then the zodiacal light would become intense enough to roast the night side.
http://en.wikipedia.org/wiki/Zodiacal_light
Even if that didn't happen, there's still the moon. If it were visible from the night side at the time of impact it would get very bright, and would probably roast the night side.
If the moon wasn't on the right side of the Earth, there's a good bet that atmospheric and oceanic effects would spread the heat to the night side fairly quickly. Normal circulation effects would go into overdrive as the temperature differences became even higher.
And finally, within a day, the Earth's rotation would make the night side the day side, even if none of the other processes mentioned brought the heat to the night side that quickly. And I'm 99.999% certain that the brightening would last for more than a day (I'm thinking somewhere from a month to a year, but I don't know for sure). If it did indeed last for less then a day, then it would have to be *very* intense to get rid of all that energy so quickly, and in that case I'm certain that between the moon, any visible planets, and the zodiacal light, the night side would be thoroughly roasted.