Just upgraded to wp 3.4 and upgraded simple sidebars. The admin side breaks until this code block:
is removed from /wp-content/plugins/genesis-simple-sidebars/includes/admin.php, and then replaced.
Here's the error I saw,
[21-Jun-2012 21:47:21] PHP Fatal error: Class 'Genesis_Admin_Basic' not found in /xxx/xxx/xxx/xxx/wp-content/plugins/genesis-simple-sidebars/includes/admin.php on line 14
Strange that it goes away when the line is removed, and added back.