eBay's highly anticipated e-Media Exchange, the proposed online auction service for buying and selling TV spots (as well as radio and print), offered a preview to advertisers and agencies last week.

While advertisers like Wal-Mart, Home Depot and Toyota are cheering the new system, cable networks are taking a more skeptical view, writes MediaWeek. Cable nets will reserve judgment on the service until they see a demonstration, according to CAB president Sean Cunningham. Meanwhile, advertisers that support the exchange have already pledged $50 million to buy ads using the system in next year's scatter market.

The e-Media Exchange was originally slated to be ready for first quarter's scatter market, but supporters are now looking at a second quarter start. Advertisers admit that cable networks will remain noncommittal until eBay begins the system's first live online beta test next month.

The e-Media Exchange is an auction-based system that allows buyers to submit budgets for ad schedules; sellers then bid for the buy in a reverse auction process. The exchange is designed to focus on cable network buys.