On Tuesday 03 November 2009 15:48:03 Patrick Lauer wrote:
> To quote:
> "FEATURES is a portage specific package manager configuration variable not
> specified in PMS and cannot reliably be used in ebuilds or eclasses."

This has been the Portage team's position for years, since long before there 
were PMS and other package managers.  See 
http://bugs.gentoo.org/show_bug.cgi?id=82513#c16 for example.