A new version of libgmail is out. (0.1.9) The new version depends on dev-python/clientcookie. I only tested dev-python/clientcookie 1.3.0 as the older version of clientcookie (0.4.19) isn't marked for amd64.
*libgmail-0.1.9 (02 May 2008) 02 May 2008; Raúl Porcel <armin76@gentoo.org> -libgmail-0.1.8.ebuild, +libgmail-0.1.9.ebuild: Version bump