I don't know any changes, but it is need to fix the depending bug.
Exactly versio 4.01 is bundled. W/o modifications.
+*libev-4.01 (25 Nov 2010) + + 25 Nov 2010; Justin Lecher <jlec@gentoo.org> +files/4.01-gentoo.patch, + +libev-4.01.ebuild: + Version Bump, #346773 +