Magazine style frontpage with multiple categories/loops and no duplicate posts

I wrote a class specifically for passing data between widgets classes using static variables and it will work for your use case as well. Grab the class here.

The way you would use this is as follows for each custom loop:

$exclude_ids  = IntermediaryData::get(); //Retrieve previous exclude IDs
$args['post__not_in'] = $exclude_ids;

//new WP_Query($args); Custom loop query

//Loop Start
     $exlude_ids[] = $post->ID,
//Loop End

IntermediaryData::set($exclude_ids); //Pass IDs to next loop