Different layouts depending on node placement (like $block->region)

Hi, Im looking to create 2 styles of teaser node for the same content type. With different layouts depending on whether the node appears in the 'content' region or the 'left sidebar'.

I'd like to use something similar to '$block->region' in my node.tpl with also including $node->type:

if ($node->type=='news'):
if ($page==0){
	if ($node->region == 'left'){
		//sidebar_left teaser layout
	} else {
		//teaser layout 2
	}
} else {
	//full news node
}
endif;

I've struggled with this on-and-off for months. I can't think of a solution to differentiate between two teasers that could possibly be displayed on the same page but in different regions.

Any help is much appreciated!
Marc