If you want to install this package, the .ebuild look for net-misc/esms, but esms are in apps-misc/esms, you must edit your /usr/portage/net-misc/gtkesms-0.0.4.ebuild , and change it.
root@vapier linux # emerge -s esms Searching... [ Results for search key : esms ] [ Applications found : 2 ] * net-misc/esms Latest version available: 0.9.5 Latest version installed: [ Not Installed ] Size of downloaded files: 32 kB Homepage: http://esms.sourceforge.net Description: A small console program to send messages to spanish cellular phones