I saw in my 3D World 112 some images from an ad for Mattoni mineral water by Velvet and Black Mountain Studios featuring a fluid water dress. The CG team have done a great job of integrating the stunning water dress with the live action footage and the supermodel. According to the 3D World notes, the dress was created in Maya, with particle forces used to manipulate the form. Houdini came into the picture then for the transformation to liquid and the rendering.
The Motionographer coverage has a few other details and a link to a quicktime video version. Here is the youtube version: