BTW, here's a link with more info and some images: http://www.skyandtelescope.com/observing/home/10862521.html
The unusual cloud around the comet is due to a sudden unexpected eruption of dust that is being lit by the sun. It suddenly increased in brightness by about a million times on 10/24/07 and is expected to remain visible for a couple of weeks. There is some speculation that it's shape may change again. It has been called "the strangest comet to appear in our lifetime." Pretty interesting stuff!