They should do, but subject to the same WebGL limitations as the Chrome browser does. In other words you need good graphics drivers, otherwise it falls back to canvas 2D rendering, just like the browser. Visiting chrome://gpu in Google Chrome on each OS will tell you what Chrome thinks of the system and whether hardware acceleration is enabled. Note you may also get canvas2d on Windows as well.
Thanks Ashley! I ask because there are people wanting to know if I'll release my game for Mac/Linux but I'm afraid to tell them I will because I'm not sure about how well it runs on those platforms.
Guess I should get someone to test it for me later.