Poynter — In Search Of: The Best Online Reading Experience. “Reading on a computer brings a new set of design challenges. And it’s way more complicated than Gutenberg might have imagined. But the good news is that there’s a lot of research being done on this topic.”
Article also has preview of new fonts that will debut with Microsoft’s Longhorn OS. Another good article from Poynter linked from the article is Eight Things You Can Do Now To Improve On-Screen Readability