WiFi in the office

I think that as soon as you make your personal info available to any corporation they will think they have the right to it. Perhaps they do, I don't know. In saying that, for security reasons they will need your MAC addresses, especially if you want access to their intranet site and other corporate information. Security is an issue for both the employee and the corporation. I would suggest that if you have personal information that you don't want them to have access to then you encrypt it on your computer.

The real danger here, IMO opinion, is the danger you open yourself to when you USE this new WIFI. Even if you encrypt your device, use of their network can be monitored. They will, should they choose to look, be able to see which devices are connected, when, for how long, what they're doing on the network, where they're going on the internet, etc.

Having said all that, as long as you're doing ok things, that should be mostly ok. Unless them knowing all that is not ok, then don't use it.

Privacy, by my definition, is not what you do over a secure web connection. Privacy is what you do at home with the doors closed, shades drawn, and communication devices turned OFF. Anything you do that connects you to the outside world should be considered unsecure, at some level. SOMEONE can know what you're doing. Make sure that's ok.

They can see you MAC address anyway, I assume they just want to aproove it.
And also, you can change your MAC address.

As soon as you change the MAC address you won't be able anymore to get Wifi access.

Of course, but he can change it before and provide a new MAC address... And when he came back home he can return old one.
I don't know why would someone bother with that but he can

I can't imagine why somebody wouldn't bother.....

its probably because they are using something similar to port guard which is on hard wired ethernet ports, they use your mac to allow you access.