To quote the PowerMac Technical Specifications page: "Networking: Dual 10/100/1000BASE-T (Gigabit) Ethernet ports; integrated wireless antenna; optional AirPort Extreme and Bluetooth 2.0 + EDR (build-to-order option or through an Apple Authorized Service Provider)
It's just not a default option as a lot of places don't need wireless with a PowerMac.
Desktops do need Bluetooth for syncing and headsets, as well as Airport for wireless-only networks or places that you don't have CAT5... and people with base stations 3" away from the computer
I believe people are asking too much for Apple to make things like these standard. Not many other PC makers even have the option to put in WiFi/BT into a desktop. Apple should not make them standard in my opinion.
But I don't like how now on the Powermac you must order both or none. Before this revision you could order the BT and Wifi module's seperate or buy them together for a savings. No you have to get both even if you need only one.