Microsoft announced yesterday via the Windows Live Blog that it plans to extend its Content Ads beta program to all US customers who wish to advertise on MSN properties. Previously, the program was limited to a small selection of advertisers and the MSN sales team, but it will now be available to the public to test out starting on August 29. The ads will be displayed on select Microsoft properties—such as Real Estate, Money, MSN, and Windows Marketplace—and will eventually expand out to other Microsoft-owned properties and “premium partner sites.” If Content Ads manage to take off as well as Google’s AdSense program, then competition between Microsoft and Google could heat up and force both to offer even better options to advertisers and, eventually, publishers.