More than 400 million smartphone and tablet users access Facebook on their mobile device--with good odds that some of them work for your organization--and soon they may start receiving ads via the social network on those devices. At the end of the month, Facebook is slated to announce some big plans for mobile advertising, reports Benny Evangelista at the San Francisco Chronicle.

Facebook expects that the pace of growth among mobile users will continue to exceed the overall pace of growth in the foreseeable future, Evangelista reports. The problem for the social network is that mobile apps don't provide enough space for the ads that appear when a user accesses the site via a computer.

Evangelista notes that there have been reports that Facebook has been testing ads that look like status updates on the News Feed but stay in view longer. There are also reports that Facebook would run ads above or within the News Feed.

As social media expert Ken Wisnefski pointed out, if it isn't careful, Facebook risks annoying users by flooding them with ads.