From the homepage...
Geary is a new email reader for GNOME designed to let you read your email quickly and effortlessly. Its interface is based on conversations, so you can easily read an entire discussion without having to click from message to message.
Created attachment 343670 [details]
Ebuild for Geary 0.3.0
This ebuild is based on the Ebuild for Geary 0.2.2 from the Elementary overlay.
I think the right category should be "mail-client".
Also, on my machine it fails while building it:
Created attachment 344762 [details]
updated geary ebuild forcing USE flag introspection to webkit-gtk (otherwise it won't build /usr/share/gir-1.0/JSCore-3.0.gir :P )
+*geary-0.3.1 (30 May 2013)
+ 30 May 2013; Julian Ospald <email@example.com> +geary-0.3.1.ebuild,
+ +files/geary-0.3.1-ayatana.patch, +files/geary-0.3.1-cflags.patch,
+ initial import wrt #436976