I have a guy a work with that wanted to work from home. His boss insisted (and rightly so) that he must be available just like he would normally be in the office. He agreed, then went to work from home. His IM client would give him away buy constantly being set to "away", which by default would happen after about 10 minutes. So, he is told you no longer get to work from home, you are always showing as away, you don't respond to things in time. After some time passes he convinced his boss to let him have another go. This time he lengthened the amount of time it takes the IM client to show as away, only he still doesn't respond to things in time, because he isn't really at his computer.
He now is not allowed to work from home, and is on the **** list.