WordPress 3.4 is shaping up to be an exciting release for theme developers.
The biggest news is that the after two years(!), the theme installer will now support child themes.
Also support for custom header sizes, new API called WP_Themes along with the removal of constants for custom headers and backgrounds.
And(!), page templates can now be placed in their own sub-directory.
http://nacin.com/2012/03/29/page-templates-in-subdirectories-new-in-wordpress-3-4/
http://core.trac.wordpress.org/changeset/20267
http://core.trac.wordpress.org/changeset/20212