A reader provides a great pointer to CherryWare on integrating your mobile with Skype and using proximity to manage your call device and PC security. He explains it like this.

"This program can trigger any command or program when your bluetooth device is out of range or back in range. I just asked it to shutdown Skype and lock my session when I walk away (out of range) thru a bat file. U:\Skype\Phone\Skype.exe /shutdown rundll32.exe user32.dll,LockWorkStation As my skype calls are redirected to my cell phone when I'm not connected, I'm getting my call on my cell phone when I'm away from my PC. When I'm back in range, I've asked the program to start Skype... so I automatically get my Skype calls back to my PC. Very simple, cheap and efficient! I think that Skype could embed that kind of stuff in the application... I guess there is a lot of new opportunities in "Skype proximity" and "Skype tracking"

The program costs USD 17 and works with Windows. I've not had time to test it yet. Let me know if you set it up and are successful. I'm not sure I understand the instruction although in principle this could work very effectively.