There have been some signifigant changes to the airspace in and around Toronto Centre that went "live" today.
As far as I understand there have been no changes in frequencies with regards to IFR traffic. VFR traffic is a different story.
All frequencies for control zones (YKZ, YYZ, YTZ, and YZD) remain the same. However the dimensions of these zones have changed.
There are new Common Frequency Areas for VFR traffic now. Three new freqs have been assigned depending on what part of the "golden horseshoe" you are in. They are: 122.9, 123.025, and 122.925).
The Toronto Terminal class C rings have had their altitudes adjusted and the shape changed a bit to accommodate Brampton Airport. As well, Terminal (on 133.4) now is responsible for the slice of airspace inside of YYZs control zone to the south just north of the lake shore of Lake Ontario. Technically this would be the responsibility of YYZ tower, but is no longer.
London airport (YXU) is now a class "C" (from a class "D").
More detailed information about the changes can be found here:
http://www.navcanada.ca/ContentDefinitionFiles/Services/ANSPrograms/LevelOfService/WTMService/WTM_Airspace_Change_March_EN.pdf
