Airport has several levels of security built-in but they are not on by default. 1. 128 bit WEP. 2. Closed networks - if you close the network then a user has to know you exist (unless they have a hardware sniffer) and also needs to know the network name and password. 3. You can set the network to only accept particular MAC addresses.
All of these are defeatable, but who is going to bother when there are so many open networks out there (intentional and unintentional).
If you use a couple of these options, you really shouldn't have to worry about security. Just keep and eye on the updates and base station flashes as Apple has been pretty responsive in terms of filling holes.
Lastly, once you are on the network, you can implement additional security as for any other wired network (via permissions, etc.).
You are right that most people forget about wireless security. There again, a lot of people who are supposedly security aware leave their computers on when they go for a coffee......
Yep. Personally, I have a closed (this is mentioned in the article in PC terminology, disabling SSID broadcasting) and encrypted network. If it wasn't for my friends coming over every so often with different computers, I'd probably use the Access control (MAC address registration) option too.
And if you leave your computer on while you are away in any kind of public place, at least have a screen saver that requires a password to get back in.