The sys-fs/ntfs3g-1.2310 needs adding sys-fs/fuse as a dependency. The older ebuilds have it there but both 1.2310 and 1.2412 haven't. Reproducible: Always
As of version 1.2121-RC (January 21, 2008) the dependency of sys-fs/fuse isn't needed anymore. New: built-in FUSE support by using a stripped down, integrated FUSE library. Linux uses this by default which means NTFS-3G doesn't require the installation of the FUSE package, only FUSE kernel support. New: the --with-fuse=external configure option makes NTFS-3G to be compiled with an external FUSE library. For non-Linux operating systems this is the default and the only compilation option. Also mentioned in the portage tree ChangeLog *ntfs3g-1.2129 (29 Jan 2008) 29 Jan 2008; Patrick McLean <chutzpah@gentoo.org> +ntfs3g-1.2129.ebuild: Version bump, dropped ppc, ppc64 and sparc keywords as this version has a completely rewritten build system and an internal FUSE implementation (bug #207120)
Frank stated it right in comment #1, ntfs-3g no longer depends on fuse, it has an internal implementation.