We just released kboard 0.9 alpha. It is a generic game interface for two player turn based board games, and currently supports a bunch of chess variants, connect four, reversi and chain reaction (and more will be added). Kboard also supports network chess play on ics servers, as well as game observation and examination. We have implemented a quite powerful generic animation engine, and a highly customizable theme specification (based on lua), that can just load everything and create shadows (default theme is SVG, skulls theme too :)).
At the moment the released code is only based on Qt4, so it should be quite portable, but we will make use of Kde when available in future releases.