Justin Osmer, product manager for MSN, said the beta version, available at beta.shopping.msn.com, is very much a work in progress. "Now that the MSN Search engine has launched, we can very quickly innovate on top of it and offer more unique features and services," Osmer said in a statement. MSN's search engine officially launched last month.

Osmer also indicated that MSN might launch other vertical search engines. "Shopping, as well as a number of other verticals, is certainly an area where we are looking to expand search into," he said. "The Instant Answers feature with Encarta and MSN Music are really just a start. The year will be all about rapid innovation for us."

A message on the beta shopping site lays out MSN's intentions: "Our focus here is to explore new ways to help you search for products, refine your search, sort results in a variety of different ways (by price, popularity, etc.), compare similar products and their cost at different stores, and to provide product ratings and reviews by shoppers like yourself."

MSN representatives declined to address revenue models for the site, but the company already serves graphic ads for the likes of Dell, Eddie Bauer, and Wal-Mart on the site's home page as well as on results pages.

The move appears to be in line with a larger vertical search trend. Jupiter Research analyst Niki Scevak, speaking at Jupiter's Search Engine Strategies conference at the beginning of March, noted that vertical search engines offer advantages over broader engines when it comes to e-commerce. "Broad-based search engines are extremely good at navigating vast amounts of information, but extremely poor at helping a consumer make a purchase decision," Scevak said.