Training groups/partners in Etobicoke

I've been looking for a swim group and/or triathlon club in Etobicoke as well. I find clubs and stores in Toronto have an east end bias when it comes to triathlons.

Chain Reaction at Dundas and Royal York have group rides for varying levels. So does racer sportif but I think it is expensive.

It all depends on what you are looking for. I know that there is a Running Room located on Bloor at about Royal York. They do a number of training runs each week that might fit for you.
There is an excellent bike shop just a bit east of that on Bloor as well (Wheels of Bloor) that is close to High Park. I don't recall whether they do group rides, but I am sure if you popped in and asked they would be willing to point you in the right direction (as well as tempt you with many great cycling goodies). This website http://www.tbn.ca/ also has links to a number of the group rides that occur in and around Toronto.
For open water swims, you are kind of stuck. There are a number of pools out in the west end - but for group OWS you will have to go downtown or to the east end. http://www.endurosport.com/experience/workouts/swimworkouts.aspx
(They apparently also have running and biking workouts you can join.)
I hope this helps!