Theming layout of OG front page
http://drupal.org/node/90149

Default theme for an organic group ( a simple workaround)
http://drupal.org/node/215914

Specific theme for one Group (snippet for a custom module)
http://drupal.org/node/272121

Default theme for a group (Issue for Organic group)
http://drupal.org/node/202442

Theming Organic Groups home page with Views, CCK and OG - problems with node-og.tpl.php and Views settings
http://drupal.org/node/116332

User interface for preferences to vary by content type or by group
http://drupal.org/node/192933