WebWorkerDaily has a nice piece on things to worry about when your office is in your house. Moste interesting point mentioned is :

Note the necessity of an "official end of your day"

Interesting. Everyone who works from home will recognize this, as often after a full day's work you receive that oe phonecall that will cost you an hour extra - unwanted but time sure flies.
I have also met several people who are addicited to their latops. They put their laptop in the living room (big mistake) and leave it on (death wish in my opinion). Personally, I have a macbook of my own and there's a laptop from the company that hired me. The last one stays in the home office - my macbook is allowed all through the house as I don't only work but also play on it if you catch my drift.

In general, if you work from home, make sure you set realistic times and limits.