Drupal 7 will consider "node" $content as a block region, which has advantages over the old "special" $content variable in Drupal 6.
Now since the $content is a block region, themer no longer needs to provide special region area in top / bottom of the node, a site builder just have to put the "top node" block in the content region and set it to be on top / bottom of the content block.
But how about if you want to "integrate" the content node block with other block region, like if you want to display a "node" content on left top while providing another custom region on the left bottom of the node while printing the rest of the node content on the right side??
Sounds complex? In drupal 6, we can achieve this by invoking