A “frosted glass” effect filter is now available in the ShaderBlow Plugin, it was adapted from here (thanks to @mifth for finding it):
Usage:
[java]
FrostedGlassFilter frostedGlassFilter = new FrostedGlassFilter();
frostedGlassFilter.setRandomFactor(0.025f);
frostedGlassFilter.setRandomScale(2.1f);
fpp.addFilter(frostedGlassFilter);
viewPort.addProcessor(fpp);[/java]