here in North America there is at least one company recovering vintage logs from the Great Lakes, this wood being over 100 years old
I know a guy who has a Godin solidbody electric nylon string guitar who says that the body is made from some of this wood. It's very dark, close-grained, and judging by the weight, very dense. Looking at the Godin website, though , I don't see any mention of this -- maybe he's wrong (he bought the guitar used), or maybe they just aren't making any more of them.
On a related note, I've seen bone material for nuts and saddles available online that is supposed to be from wooly mammoths -- that would go good with some of that 50,000 year old wood!