finding usergroups in $post[]

[dethfire]

I know how to find usergroups for the person browsing the forum with is_member_of()

however I want to figure out the usergroup of each post. I want a graphic to display in a postbit if the usergroup of the member of the post is a certain usergroup. How can I do this?

[NTLDR]

<if condition="is_member_of($post, USERGROUPID)">code to show</if>

Obviously changing USERGROUPID to the ID of the usergroup your checking against.