Workbenches work the same as they did in L4. However, the current dev of L5 does not properly load workbenches.

A temporary work-around is to add the following to your bootstrap/autoload.php and delete your storage/framework/compiled.php file.

/*
|--------------------------------------------------------------------------
| Register The Workbench Loaders
|--------------------------------------------------------------------------
|
| The Laravel workbench provides a convenient place to develop packages
| when working locally. However we will need to load in the Composer
| auto-load files for the packages so that these can be used here.
|
*/

if (is_dir($workbench = __DIR__.'/../workbench'))
{
	Illuminate\Workbench\Starter::start($workbench);
}