Our forum topics seems to get the meta descriptions from the wrong part.
See part <meta property="og:description" .. is not the same as the actual content.
Example url: http://trolltrumman.net/f/topic/samisk-schaman/
Also notice that plugin "All in One SEO Pack" uses the correct part.
bbPress 2.4.1, NGFB 6.14.0 (GPL)