The Inq spotted a 450W power supply from JSP Tech at Computex which features watercooling and a CPU block.
It will retail for about $150 when it comes out in the near future.
On one hand, it makes a lot of sense, you have a direct external exhaust and a large area to put a radiator on. On the other hand, water + AC = bad. I will leave it up to the reader to decide if this is a good idea or not, but it certainly is different.