Why write my own if an excelent reference exists in the Mac Mini Wiki.

Some other sites are listed here:

• Linux on the Mac Mini
• Mactel Linux Wiki
• Mac Bidouille is a very nice site with great tutorials - in french only though.

 It's because it really is an AUDIO IN PORT, not a low voltage MICROPHONE PORT!

It requires 1 V pp line level voltages, and you bought an off the shelf dynamic microphone that only puts out a few millivolts.

You'll need something that brings the microphone levels up to line level. You could use an old cassette deck with MIC IN and HEADPHONE OUT in a pinch, or use a dedicated MIC amp that bumps up the signal level.

Old Macs like the LC III and such did use a basic MIC INPUT port, but later Macs switched to LINE INPUT so they'd work with signals coming from stereo systems, etc. Apple made a LINE LEVEL MIC with an extra long tip that gets power off an extra contact point in Mac models even as recent as a G4 tower .

The real question is, did Apple keep backward support for this microphone? If so, is it possible to find one? However, you'd lose your advantages of a headset microphone...

The best solution so far is the iMic which provides all required interfaces to plug in a standard headset. Details about the Linux support can be found here

Remember, the port is actually a STEREO INPUT port, so this may also mean you would need to use some STEREO to MONO adapters or find a software setting that will put one channel across both left and right as a MONO signal.  

 Note - in case you use Ubuntu 11.04 - you don't need to do this - it works out of the box already.

If a btusb module is loaded - unload it first with

sudo rmmod btusb

Download and install this debian package: btusb-dkms_0.0.1_all.deb

Install the extracted deb file. Problem is that this file is made for older kernels. So - all we do - is install it, and replace the btusb.c file later to avoid the error.
Install with

sudo dpkg -i btusb-dkms_0.0.1_all.deb 

Download the replacement btusb.c and replace /usr/src/btusb-0.0.1/btusb.c with it.

After that, run compile and install the new module in the terminal, using this as a guideline:

sudo dkms remove -m btusb -v 0.0.1 --all
sudo dkms add -m btusb -v 0.0.1
sudo dkms build -m btusb -v 0.0.1
sudo dkms install -m btusb -v 0.0.1
sudo modprobe btusb

Finally, restart the bluetooth service with:

sudo service bluetooth start

You can get rid of the dpkg error message by downloading the following file and copying it to /usr/src. Run sudo apt-get install -f to remove installer error message.

Note - the data and the code on this page has been copied from Mac Book Pro/Ubuntu Maverick thread, as I'm too lazy to remember the Link every time I have to fix it on my mac mini. So - Thx to the community for the info.