Not just dual pricing, but the ability to have different customer groups and different pricing for those customer groups.  Simply saying that when a customer logs in and is classified as a "wholesaler" the price of the product displayed will be changed to reflect the customer group pricing.

Yes multi level price levels... customer accounts can be assigned retail, wholesale, a % off etc... each level would be a % off from retail pricing... and perhaps have choice to not discount sale items, or perhaps be able to assign only certain products/categories to each price level as well... thus if a certain reseller only gets a discount on all the products you make but not the products you bring in etc.