To block Beacon ads, just add the URL http://www.facebook.com/beacon/* to your ad-blocking tool. If you don't have one, these instructions will set you up on Firefox.
Social Ads will supposedly use the news feed URL http://www.facebook.com/stories.php?filter=28. We at the 'Wag haven't seen any yet. But hopefully they'll be adjustable via the News Feed Preferences page, as are other numeric categories. If Facebook won't let you customize your feed not to show any #28 items, expect a Greasemonkey hack to appear shortly.