MSN THIS WEEK SENT OUT invitations for a closed beta test for a program that will place text ads on publisher sites.

The program, Content Ads, will initially involve placing ads only on Microsoft properties, including MSN Money, MSN Real Estate, and Windows Live sites. But MSN is expected to extend the program to other publishers’ sites.

This week, the company sent an invitation to advertisers, inviting them into a beta test. The invitation, posted on the blog JenSense, said Content Ads would allow marketers to distribute search ads “primarily” on other Microsoft properties. Industry observers took the word “primarily” as an indication that the company intends to eventually include non-Microsoft publishers, much like Google’s AdSense and the Yahoo Publisher Network.

Find out more about MSN’s contextual advertising program athttp://publications.mediapost.com/index.cfm?fuseaction=Articles.showArticleHomePage&art_aid=47537.