I am! I went down south this past summer and caught a nice mackerel from my kayak. I was a little unsure and unbalanced at first, but once I settled in and relaxed I had a blast.
I've got a 16' Perception Carolina that I rigged with rod holders and such. I'm hoping to take it out on the Feather River next September during salmon season and try my luck. I live right along the Feather, so I've gone out and explored the area several times, but I have yet to try to fish it from my yak. I'll admit, I'm a little nervous about the prospect of being dragged around in my kayak by a 30+ lb fish....should be quite a ride.
I've also taken it out on Folsom quite a bit, and have gone out on Lake Tahoe a few times. But I've only fished on it twice, so I need a little more practice before I take on a salmon.