I've released a houdini version (compiled for windows x64 11.0.658) of my cuda fluid solver with the source code.
It's pretty basic, only sphere emitters and colliders, I made it to learn cuda and the HDK. It's fast though.
Little demo vid : http://www.vimeo.com/21619389
More info and download : http://www.foliativ.net/book/index.php?post/2011/03/04/Cuda-Fluid-Solver-Plugin
I hope to improve it in the future but don't hold your breath as I don't have much free time currently.