It would be nice if Portage can log to a file what is being emerged and any messages put out by Portage during the install process (those messages proceeded by a colored asterisk). When several things are being emerged those messages can be easily lost and sometimes they are important.
/var/log/emerge.log in portage-2.0.47_pre4 and later per-ebuild logging can be done.
*** This bug has been marked as a duplicate of 4552 ***