How do I disable secondary display connective via HDMI on Lion/Mini? I have a late 2011 mini and the HDMI out is set up to go to my receiver and thence to my TV. When the TV is off, I would like it not to extend my desktop to it, but it is. How can I prevent that other than plugging and unplugging the HDMI cable?

Update: covers similar ground to Best practices for 2011 Mac mini connected to monitor + HDTV?
I had the same problem, this happens because the TV is still sending a signal to the HDMI port even when powered off so the Mac still thinks that it's active. To solve this you need a HDMI switcher that will fully kill the HDMI signal when it's not used. Here is the one I use:

http://www.amazon.com/Ultra-High-Performance-Switcher-Switch/dp/B0015YWKYY/ref=sr_1_1?ie=UTF8&amp;qid=1328391227&amp;sr=8-1