According to the Wall Street Journal, Microsoft recently considered entering the e-commerce market. Rolling out an e-commerce site would have put Microsoft in direct competition with Amazon and Ebay, the two current market leaders in the e-commerce market.
A Microsoft spokesperson confirmed the program:
Project Brazil was an incubation to enable a more direct commerce model between customers and brands and merchants. We remain committed to finding new and differentiated ways to enable a richer, more task oriented approach to e-commerce and online advertising.
E-commerce is an important marketplace. The market continues to expand, with estimates saying it will reach $1.3 trillion this year, which is up 18 percent from last year. The e-commerce site would have been part of Windows and eventually other products such as Xbox and Windows Phone. Source #1 below has the full details.