I've updated simple zen for 1.3.7 (may take a bit to show up in the download section).

Here are the changes made (from readme.txt):
v1.9 updated includes/templates/simple_zen/common/tpl_main_page for 1.3.7. Have moved the older tpl_main_page.php to the "pre-1.3.7 files" folder. Updates to the stylesheet (cosmetic tweaks, plus 1.3.7 updates). Also added buttons that are new in 1.3.7 in the includes/templates/simple_zen/buttons/english/ folder. Small changes were made to includes/templates/simple_zen/common/tpl_header.php