Years back, I had been of some help in readying a Kannada font for Mac OS X. It was a Mac OS X port of Kedage font. I had no Mac device with me then.
Through Sampada, I used to get several emails from Kannadigas around the globe requesting information about getting to read Kannada on devices running Mac OS X.
Things have changed a lot since then. Mac OS X now supports Kannada out-of-box although the font supplied is not the best available. If you end up buying the latest Macbook Air or Macbook Pro running 10.8 Mountain Lion, the rendering is quite good - except for few bugs in the fonts supplied out of box.
However, on Mac OS X 10.6 (Snow Leopard) and on Mac OS X 10.7 (Lion), I've tested and found that by using the Kedage font or Sangam MN (if you get a copy of that) you can get to read Kannada pretty fine. The rendering is close to flawless, except for few (negligible for the moment) issues.
Alright, that is about being able to read Kannada text on Mac. How about typing in Kannada?
This was something that many people have kept asking for a long time. I used to get many emails on Sampada that had queries about just this. I still keep getting email requests on how to achieve this on Mac OS X, so here's the status as I know it (and based on what I tried) and a workaround that has been quite a good option so far:
Apple provides a set of input methods out of box and there are two input methods available for Kannada on that list - Kannada and Kannada QWERTY. The input source Kannada is a take on NUDI or K P Rao method of input for Kannada. However, it doesn't work as it should. Kannada QWERTY is an implementation of Inscript keyboard layout which seems to work for most part, but I haven't had a chance to test it fully. These two methods are probably the most used in the journalism and media circles here in the state. The other popular input style or layout that is quite popular among Kannadigas is Baraha style (an adaptation of itrans modified to suit the Kannada users) which is not included in Mac OS X.