I am on a mac pro 2009 and use the "Logitech Pro 9000" (PC Version) usb Camera without a problem for about a year.
Today I tried to do a skype video call again with one of my friends and discovered that the microphone didn't work at all on my OSX Snow Leopard 10.6.5.
First I checked the preferences on my mac osx. No good luck there.
I tried to check the camera on Windows / Virtual Machine (Fussion 3) and discovered that the microphone didn't work at windows neither. (I had a hope that maybe something was "Stuck" for the camera and that if windows with the native windows drivers of the camera could "see" the camera in it's nature environment, it should be un-stucked or something...!!! Lool..!!!!) (If you find my "windows seek for help" behavior strange read bellow for an old linux problem I had once, when a USB HDD Stacked and couldn't mount to my linux system because it was not properly unmounted on windows (unmount on windows = "Safely Eject Hardware"). After a lot of search for the HDD issue solution on many linux forums, I found that I had to mount and unmount the usb hdd on windows. Then go on linux and mount as usually the HDD. The problem on linux mounting an unproperly unmounted USB HDD from windows solved and I thought that some kind of "same logic" could solve the problem for the mic of the logitech camera too...Looll...but I was almost wrong...!!!!)

I Played somehow with the properties (on windows) for the camera microphone and found that it was muted. I un-muted it and at the properties panel I saw that the green bars was moving (indicating that the device was receiving sounds through the logitech's mic. I opened on windows the program of the logitech to record a video with sound and the mic was not enabled.
That was the 1st indication that the problem is software problem and not hardware problem (the mic is still working) and somehow it get muted...!!!!?
I even reseted PRAM on my mac pro by rebooting my machine and pressing the Command+Option+P+R until the white screen appears (see the apple way of doing reset PRAM on your model of mac and for more details).
The reset of PRAM on my mac pro didn't work.
I Googled it more and found that if you go to "Applications/Utilities/" and Run the "Audio Midi Setup.app" in the list of the devices you will find a device "unknown USB Audio Device" (it will have the symbol/icon of the mic). If you select it and check at the right of the application GUI you will discover that for some strange reason the mic is muted. Un-mute it and everything will play normally...!!!!
Now the device have the mic again enabled (un-muted).
I really don't know why this suddenly happened, but by doing what I described earlier, should solve your "mic problem". It worked for me. The problem of the camera is not because you have a mac mini. Mac's usually don't have problems with the devices. If the drivers exist for mac's, usually it recognize them automatically in 2-3 seconds. It must be a logitech's driver bug or something. (I was using this camera for a almost a year before the mic problem occurred. Nothing was changed in my mac devices from the time it worked until today that it stopped working suddenly)
I hope my info helps you solve your problem with the camera.
Cheers...!!!
