To make it a bit more clear:
in my form (for edit and new) I have the following:
<% for menu in Menu.find(:all) %>
<tr>
<td><%= check_box_tag "group[menu_ids][]", menu.id,
@group.menus.include?(menu) %></td>
<td><%= menu.title %></td>
</tr>
<% end %>
But this is not for what i would like ! (if it is even possible 
)
