Escape Motions (http://www.escapemotions.com) has released Rebelle, a watercolor and acrylic painting application for Mac OS X. Its watercolor simulation is based on a real-world color mixing, blending, wet- diffusion, and drying.
Rebelle mimics the way natural media interacts with the canvas and itself. Users can paint, smear, re-wet dried colors, blow wet washes across the paper, tilt the paper to create water drops and runs and create countless fantastic watercolor effects. Wet tools — watercolors, acrylics or ink pen — can be combined with pastels, pencils, airbrush many other dry-media tools and effects.
Rebelle is available for US$59.99 at the Escape Motions website. A Mac App Store edition will be available soon.