Thankfully a simple workaround exists, that requires you to edit /etc/sudoers.
sudo visudo (Don't use vim direct on /etc/sudoers)in the Default specification section add:
Essentially when you sudo port install apache2 sudo only takes a stripped down version of current environment variables, so even though you have set your all important $http_proxy, macports doesn't get it. Adding those two lines will fix that. Now install software galore!
Defaults env_keep += "http_proxy HTTP_PROXY HTTPS_PROXY FTP_PROXY"
Defaults env_keep += "ALL_PROXY NO_PROXY"