The Ontario Superior Court of Justice just released a decision saying that there is no free-standing tort of invasion of privacy in Ontario. For more detail see the Jones v Tsige decision (pdf), and commentary by David Fraser and All About Information.
The Ontario Court of Appeal in its decision in R v Cole talks about an employee’s expectation of privacy on a work computer. For more detail see commentary by David Fraser and Dan Michaluk. This decision was very fact driven, and found that there was an expectation of privacy for a work laptop for which the employee had permission to use for personal work, and to take home. It tempered that expectation by an implied right of access by IT personnel to service and maintain the network. And explicit company policies can counter that expectation.
So if your business does not have a technology use policy that addreses this issue, you should consider implementing one.