Will Rio release an FM modulator for the Karma to hook up to factory car stereos? If not, can someone recommend a good quality one that will work with the Karma?

better yet, an FM tuner addon would be cool
b

Is an FM modulator your only option?
If your headunit has a CD changer input you maybe able to get a Blitzsafe adaptor for it.

I do not believe an FM modulator is in the plans. There are already plenty of third party products which fill this gap.

But I must say, I much prefer going this route. The quality is much much better than an FM modulator would be.

I've now got a small 1/8" jack on the dash of my wife's car (in the side of the goody pocket below the stereo) and we keep a short 1/8" male-to-male cable in the glove compartment. When I get into her car, I just bring the Karma (nothing else, just the Karma itself, it's got more than ten hours playback time with a charged battery) and we can listen through her CD changer input.

Just a note... I was going to use Tony's technique, but Sony's ports are proprietary. Sony HUs need an adaptor that costs around $100. It's very cool and available at Crutchfield's. (This all may be worthless information, so disregard at will.)

I am going this route with the FM modulator. This is better for me because it is cheaper than the adapters from rcainput.com, and I plan on selling my car in a couple months and I want to use this setup in the next car without buying another adapter.