The online classified space has seen a lot of activity in recent weeks by a lot of companies taking a lot of different approaches. Oodle.com continues to grow with its business model of bringing buyers to existing ad-seller sites. Google Base is beta-testing its big brand name as a marketing site where users can post whatever content they wish, including retail goods for sale. Even eBay is in the classifieds business, and last week saw the launch of Vast.com, an online classified player that says it has 15 million listings scraped from 50,000 Web sites. Now into this fray steps Microsoft.