I was taught that serif leads to slower reading and greater comprehension, and that sans facilitates skimming. So, I find the choice of serif a bit counter intuitive for a message board. In this train of though I would expect the title to be serif and the body sans, but it's just the opposite here.
I find those old saws about serif vs. sans serif to be generalizations, and depends greatly on the typeface, application, and personal preference. Georgia, the serif face chosen here, has a larger x-height and old-style-figures as designed by Matthew Carter expressly for screen display and at relatively small sizes. I personally find it very legible, and less straining than the vertical repetition of Arial or Verdana.
From a design standpoint, I also don't like the sans serif web typeface choices of Arial or Verdana, they just aren't as pleasing to me as Georgia. Trebuchet is OK in small doses, but is a bit informal, and Helvetica renders inconsistently between browsers and platforms, and is not universal.
Of course this is my opinion, and those of you who prefer sans serif have that choice.