John,
I have turned a lot of Hickory and, like others have said, it turns great when it's green. When it's dry it's like concrete so sharp tool are an absolute must so sharpen often because they dull quickly. Hickory also splits readily as it dries so be very cautious with what ever drying method you choose. I've had success with Dave Smith's DNA process.
We turners use what is called the 10% rule when rough turning green wood to dry before finish turning it. This means leaving a wall thickness in your rough turned bowl of 10% of the diameter. However, my experience with Hickory would be to leave more than just the 10% because the Hickory I have seems to warp more than some of the other wood species. Also, if (actually, when) it develops surface cracks in the drying process, you should be able to turn past these when you finish turning.
I hope this helps.