Apple has re-added refurbished iPhone units to the Apple Store Online. Refurbished iPhone units are available in limited supplies, from time to time. These units usually sell out quickly, due to their limited supply and discounted prices.
Currently, Apple is stocking only the 8 GB iPhone model. It is now available for $349.00 with free shipping. That’s $50 off the price of the current (non-refurbished) 8 GB model. It is the lowest price Apple has ever sold the 8 GB model of iPhone for directly.
Apple refurbished products feature a full one-year warranty, and are are treated as-new, eligible for AppleCare Protection Plan extended warranties and support options.
Update: Currently sold out. Bookmark this link to check the current status, Apple adds refurbished stock at random intervals.