What counts in social bookmarking is participation. And by that I mean actually submitting stuff that has nothing to do with your site in most cases.

As for "automating" the process of social bookmarking with services like socialmarker I would stay away from. As you wouldn't want your site blacklisted from social bookmarking sites. Besides most of those sites with the exception of tipd and propeller and mixx would not have any interest in real estate related bookmarks.