The power draw and heat output of the Xbox 360 has been a bone of contention to some. Not only to reduce their own costs but satisfy power-concerned customers, Microsoft has been planning a hardware upgrade to the 360 in the form of switching from 90nm to 65nm processors. This manufacturing upgrade is getting delayed, and won't be rolled out until mid 2007.
This really has no impact on existing 360 owners, but if you were holding out on buying one until the newer CPUs made them less hot, slightly less noisy and perhaps a bit cheaper, you'll have to wait a big longer. Other price cuts may soon come, as Microsoft has made it clear that they have entered the point in manufacturing where the cost of the 360 is less than what it is sold for. This also doesn't make any impact on the noise of the disc drive, but it is a very novel and interesting thing to see a console being updated over a year after it's release to make it more attractive.