Sorry, but you're wrong. From Wikipedia:

"Pre-shared key mode (PSK, also known as Personal mode) is designed for home and small office networks that don't require the complexity of an 802.1X authentication server"

and also

"WPA-Personal
Also referred to as WPA-PSK (Pre-shared key) mode, it is designed for home and small office networks and doesn't require an authentication server. Each wireless network device authenticates with the access point using the same 256-bit key generated from a password or passphrase."

The same 256-bit key. No authentication server required! And none mentioned in the tip either. FWIW "WPA Personal" is how OS X refers to it too. The type you're referring to, requiring an authentication server, is referred to by OS X as WPA Enterprise.