Brilliantly designed maintenance page. Charming and funny copy reassures users that the service will be back soon, and gives them stuff to do in the meantime. Twitter updates let OCD types check back every now and then for a (perhaps illusory) fix of progress and control. Blog updates do the same. And - very importantly - they don't lock users out of their account details and other such important things during maintenance.
And of course, it just looks all clean, cuddly and wonderful. Shineh!