You know... I appreciate all your helpful "if you want to move portage to /var you can do it by..." 'suggestions', but, can you imagine the following situation:
You push a change to a repository, on your way to work you realize that there was an error in the commit so as soon as you get to work you send out an email to everyone "Please do not pull until today evening when I have reverted that". And when you're back home and check the status you see that about everyone who could possibly have read you mail pulled from the repo. A parabel for the technically affine...