As far as I know, Home Depot is coming to town. They have already started preparing the site. It will be located across the street from Auburn Nissan behind Les Schwab and the GMC dealership.
Trader Joes is not coming to Auburn anytime soon

From the Sentinel:
RUMOR MILL – The Trader Joe’s rumor should be dead and buried, but it isn’t. The Two-Buck Chuck supplier for the area has no plans to open a store in Auburn in the next five years. That’s what their corporate office told me when I phoned after the rumors started flying initially. They are not going into the old Ralph’s store, which is being carved up into two smaller shops to make the building easier to lease. That doesn’t mean they will never open a store in Auburn and when the checkers were getting zip codes from customers, I’m sure they discovered that many came from this area. We have about four years left on that “five year plan” I mentioned earlier, so there is still a chance they could wind up in Auburn by 2011.