I worked for a telecommunications company in the UK for 5 years. We produced software that logged the call details of every phone call coming into and out of a company's telephone switch. No they don't record the phone call itself, it's a lot more boring than that, and a lot more useful if you want to sack someone.
Their phone system, they can do as they wish as long as it's not actually listening in on the call.
There were plenty of good reasons for having the software - Police forces would keep track of response times to 999 calls, Hotels would charge customers, RAF and Army would keep track of phone card use, businesses would keep track of their customer support response times.
But they'd also keep track of the calls you made, to whom, how often and whether that could be considered abuse. They would keep track of when employees ignored phone calls, and which extensions ignored them, and in which order. I ran the software myself and could tell if the helpdesk people I managed bumped the calls of difficult customers to the next person in line, and then the next person and so on until someone finally answered.
Believe me when I say we dealt with the largest employers in the country - and if we had offered them the ability to track web use or read outgoing email, I doubt a single one of them would have turned it down. At least not unless it was proven illegal. I recall the court cases involving tracking the internet use of local authority computers, and all of them have said the employee has no expectation or right to privacy when using publicly funded computers. I doubt they'd rule any differently for private business. You don't own the computer you use, the company does, and therefore it has the right to know what and how it's been used by its employees. If you think using IM or blogs are in the best interests of your company, I'd make sure someone in management not only agrees, but writes and signs something to that effect. Unfortunately it's unlikely, because not most management fail to see how the massive advantages these tools can give.