An article titled "`Smart' meters have security holes" shows that smart meters can be hacked, and that this can allow malicious parties to both tamper with a user's security bill and actually control the supply of power.
I think that use of IT systems in critical circumstances such as this (because your home security is indeed critical) is a big mistake. Our work and leisure (not to mention time and money) is already at stake every day with the vulnerabilities that our computers contain. Extending this insecurity to the power grid is simply insane. In a few years' time, when IT becomes even more central in our lives, hackers will probably be able to control the doors to our homes.