I changed all the occurences of is_site_admin to is_admin (or is_super_admin if you’re running multisites)
Then on line 172 where it lists
add_submenu_page('wpmu-admin.php', __('WordPress Hashcash'), __('WordPress Hashcash'), 'manage_options', 'wphc_admin', 'wphc_admin_options');
I changed this to
add_submenu_page('options-general.php', __('WordPress Hashcash'), __('WordPress Hashcash'), 'manage_options', 'wphc_admin', 'wphc_admin_options');
and it now shows under the Settings menu.
This is for 3.x
Dan, got a problem with the admin search functionality on Manage > Posts which seems to stop working when the plugin is enabled. Can you shed some light?
