Is Multiple-Column Online Text Better? It Depends!
http://www.surl.org/usabilitynews/72/columns.asp

Baker, J. Ryan
Usability News
2005

Abstract:

This study investigated the effects of multi-column displays and justification on reading performance and satisfaction of an online narrative passage. Participants read a short story displayed in one of six formats (one, two, or three columns, in either a full or left-justified format). Results showed a significant column x justification interaction with reading speed significantly faster for the two-column full-justified text than for one-column full-justified, and significantly faster for one-column left-justified than for one-column full-justified or three-column full-justified text. Post-hoc analyses indicate that the faster readers may have benefited most from the two-column justified format.