This is a great tip a friend gave me the other day. The elog summary is great to get some of the warning messages and instructions, but you can have those email to you, and get more information! This is extremely simple.. and can really save some time debugging a emerge. Simply add this to your /etc/make.conf file
PORTAGE_ELOG_CLASSES="warn error log"
Obviously change the firstname.lastname@example.org to your logging email account, and you'll get nice portage messages.