Good to leave your Wifi open?

There's a lot of buzz lately about Bruce Schneier's new essay on how great it is to run an open wireless network at home. My take on this is going to be short and sweet: You're crazy if you leave your wifi open. Here's what can or will happen if you don't secure your wifi:

• Your own download speeds suffer as neighbors' infected laptops find a new vector to spew spam and malware.
• You'll find your home IP address blacklisted and receiving spam complaints over bad stuff people send via your connection.
• The buck stops with you. Your ISP can trace it as far as you and no further. This means that if somebody uses your wifi network to send spam, or traffic in kiddie porn, you're the one whose door the feds or the FTC are going to knock on.
• Running a mail server? You'll get blacklisted due to all of the above.

When I lived in Minnesota, I inadvertently left my wifi access point unsecured for a period of time -- and I did find mail server blacklisted. A neighbor's infected laptop used my connection to send spam. I was pretty embarrassed about it at the time -- an anti-spam guy's IP address was being used to send spam! It just highlighted for me how it's not wise to tempt fate. It might be really neat to leave your car unlocked, with the keys inside, so your neighbors can borrow it as needed. But, is it wise? C'mon, people!