The position after 39.S14 was posted on BoardGameGeek as a puzzle, black to move and win.
See http://www.boardgamegeek.com/geeklist/51810/item/1470038#item1470038 and scroll down to the next entry.

But I don't think 40.o9 works. For example,

|41.o8 42.p11 43.n10 44.o14 45.q12 46.r12 47.m12 48.q13 49.s13

However. 40.P12 looks good:

|40.p12 41.q12 42.o10 43.m9 44.n12 OR

|40.p12 41.p11 42.q10 43.q14 44.o9

Here are a couple more variations to show that 40.o9 does not work, but P12 does:

|41.o8 42.q10 43.n10 44.p12 45.n15 46.n13 47.n14 48.l11 49.m12

|40.p12 41.n15 42.n13 43.n14 44.m10

Just a quick thought: what if |41.o8 42.o11 (threatening p13, strong connection to the t8-t12 group, double threat at m10 and o15)?

You're right Alan. For example |41.o8 42.o11 43.q10 44.q11 and white is toast.

So, o8 does work, but so does p12, so the puzzle has more than one solution.

Perhaps a better puzzle would be the position after |41.o8, to find o11.