[eBay CTO] Matt Carey, the former chief technology officer of Wal-Mart ... said he was working on building computer systems that can look at customers' past purchases and make educated assumptions about what they might be looking for.When I worked on Amazon Auctions back in 1999, I implemented a nifty recommendation feature for that site. It was a feature I was not supposed to be working on -- it had been cut from the required features for launch -- but it was too cool not to do, so I built it anyway.
The feature was pulled on the demands of a SVP a few weeks after launch. It was yanked not because it was not effective -- it easily and overwhelmingly won in A/B tests -- but because it generated complaints from sellers who did not like competitors' items shown next to theirs.
I still think the feature was the right thing for buyers and, in the long term, the right thing for sellers. Seven years later, it will be interesting to see what happens as eBay experiments with recommendations.
Update: By the way, don't miss the details on how eBay's systems have evolved over the years in this 2006 talk on eBay's architecture.
Update: Seven months later, a BusinessWeek article claims eBay is "trying to make [the shopping experience] simpler, more personalized, and more relevant" and that eBay will "recommend items to users based on their shopping history and the shopping histories of other people like them."