My Better Half, and a quick commenter, independently suggested I try a legendary remedy they had heard about, namely washing the keyboard in the dishwasher (figures bloomin' Boing Boing had already tried it - as I just found out).
So I did.
The keyboard is a white and beige medium quality Mac desktop keyboard, USB plug, transparent case, about three years old I think (can't remember if it is original or if I passed that to a postdoc and confiscated a newer keyboard).
It was working, with regular layer of "office grime" on it (ie you could see which keys are most heavily used, and there was some dust and minor detritus visible between keys).
The coffee spill was primarily on the left side, although coffee was visibly pooled along the length of the lower half of the keyboard.
The keyboard was completely non-functional after the spill, and after it air dried it was functionally useless. Most of the keys were either non-functional or produced garbage output, maybe 10-20% of the keys produced correct output.
The keyboard was taken home and put in a household dishwasher. It was the only item in the dishwasher, and was run on a warm water rinse cycle, no soap.
After washing the keyboard was airdried and then taken back to the office.
In the office I turned off my snazzy new bluetooth keyboard and plugged the old one in.
Not back to 100%, three keys on the bottom left corner (SHIFT, CAPLOCK and CTRL) are not working, but there is a duplicate set on the right corner. Every other key works as it should.
So the keyboard works, but is retired as a future spare, since not having the left corner keys is a minor nuisance (I tend to use the left side for those functions).
I did something slightly less traumatic a while ago to a logitech keyboard and spilled a glass of water on it. After not waiting long enough for it to dry I grew frustrated waiting and simply disassembled the whole thing and then let it dry. It took a couple tries to get it reassembled with all the keys working, but it is now working again (and has been working perfectly for more than a year after the water on it)
You may want to try this one to get your keyboard back, almost in its initial state.
I clean mines at least once per year and after each coffee shower :-)
One night I was working on a new motherboard and I managed to spill a drink, soaking the board completely. I rinsed it off wit clear water and followed that with a rinse of alcohol, no joy. At a previous job we had used a dishwasher to clean circuit boards in production so I figured what the heck it can't hurt. I ran the board through a washer cycle and after I had air dried the board, it worked. I never considered trying it on a keyboard. Thanks for the tip.
Apple has released a new keyboard, so you cannot replace your old one with same style. IF you act fast, you can buy the previous edition. I know of, for example, one astrophysicist with no less than four of the previous edition in his office.
Makes ya think... why don't they have a duplicate of ALL the keys on a keyboard, and not just some of them?