From the ARRL web site, dated 2/14/12:
On February 6, Radio Amateurs of Canada (RAC) issued a statement on their website that the Ontario Section would be split into four new RAC Administrative Sections, effective September 1, 2012. The reason given for the restructure was “...to create a management model that better communicates with, and represents the interests of, the overall Ontario Amateur population.” The Ontario Section will be dissolved and be replaced with four new RAC Sections: Ontario North, Ontario South, Ontario East and the Greater Toronto Area. The new section abbreviations will be announced when final.
More ARRL info on this topic is here: http://www.arrl.org/news/rac-to-split-ontario-into-four-sections
Radio Amateurs of Canada (RAC) info on this topic is available here: http://www.rac.ca/en/news/bulletins/2012/6/