I'm wondering what is the longest fermentation you have encountered. I
> have a couple batches of mead that are still fermenting and we're coming
> up on two years!!!
I've never had a fermentation last that long, but years ago I heard of a trockenbeerenauslese in Germany that came in at such high Brix that it took about 40 years to ferment.
Of course, this could be urban myth - or at least somewhat exaggerated.
Tom S