The Toronto Transit Commission - TTC - serves the city of Toronto with bus, subway, streetcar, and paratransit. GO Transit provides commuter rail service from the suburbs to the city.
TTC Subway - Right now, there are 29 stations that provide barrier-free access to subway trains. That is a little less than half of the stations. On the TTC website, you can get a list of those stations. Another 14 stations are planned to be accessible within the next 4 years.
TTC Bus - 92% of the vehicles in the bus fleet are accessible. By the end of 2011, it is expected that 100% of the fleet will be wheelchair accessible. Three all-night routes (301, 306, and 352) and one downtown express route (141) are not listed as accessible, the rest are. You can go to the TTC website to get a list and map of all the bus routes.
TTC Streetcar - The Toronto Streetcars are not wheelchair accessible. The TTC plans to start introducing low-floor accessible streetcars in 2012 with the entire fleet done by 2018.
TTC Wheel-Trans - The TTC's version of paratransit requires an in person interview before approval to ride making it inconvenient for travelers. Here are the procedures for approval.
The current base fare for all TTC services is $3 (CDN) and a day pass is $10. Seniors 65 or older get a one dollar discount on the base fare, there is no discount for disabled riders.
GO Transit - The commuter rail service provides double-decker trains into downtown Toronto's Union Station from Niagara Falls/Kitchner-Waterloo in the west; Orangeville, Barrie, and Beaverton to the north; Stouffville, Uxbridge, and Peterborough to the northeast; and Oshawa/Newcastle to the east. All but 10 of the 59 stations in the system are accessible and 6 more are slated to be accessible by the end of 2010. Fares run from about $4 one way to around $18 one way. Their website has a fare calculator.
Many nearby towns have their own bus systems that connect with the outer reaches of the TTC or GO systems. You can find a list with links here.