eBay (NASDAQ: EBAY) has decided to move its advertising back to Google (NASDAQ: GOOG). But the auction site said it does not really need the search engine.

During the 10-day period that eBay pulled its ads, the company claims that its audience and auction results did just fine. According to eBay management, it got help from Microsoft (NASDAQ: MSFT)'s MSN, AOL, and Yahoo! (NASDAQ: YHOO) to keep leads coming to its websites.

eBay pulled its ads from Google when the search engine tried to throw a party for its CheckOut business during a gathering of clients that use eBay's PayPal. eBay saw the move as a way for Google to take customers in broad daylight.

The whole incident creates a mystery that may remain in place for some time. If eBay does not need Google, why go back? The firm says that its ad commitment going forward will be more modest than in the past, but if MSN, AOL, and Yahoo! deliver such good results and do not compete in the online payment business, why not stay away from Google for good?

There could be two answers. The first is that eBay is being disingenuous about the effectiveness of Google's AdWord program and can't do without it. The other is that eBay may be getting ready to announce a large deal with the three other portals, perhaps one that would involve them using PayPal. In essence, they would be creating an alliance to compete with the largest search engine.

Maybe.

Douglas A. McIntyre is a partner at 24/7 Wall St.