multiple post admin menus WITHOUT using custom post types

I am trying to make a complicated ecommerce theme more user freindly.
The theme uses a ton of custom fields to add products via the posts menu.

I would like to replicate the functionality of custom post types in wordpress 3 that would allow a separate menu item for different post types (and allow custom meta boxes under the menu ‘new_post_type’>new post) BUT i dont wont to actually separate them in the database, and they need to show in a standard loop, so i dont want to actually use a new post type.

I can just add custom meta boxes to the regular post interface, but that will confuse publishers who are trying to post regular blog posts.

Is this possible? im sure it is, but i cant quite get my head around it.
There are a lot of bad implementations of custom post types going around and i dont want to be one!