hg tip doesn't work well at all on Xinerama for me. I have ~20 applications. By default they all end up on a single monitor (expected), but they aren't tiled properly. No window was placed in the master area and the stacking region was not full (there was a large gap). The status bar seems wrong - on monitor 1 (which has no applications), tag 1 is shown as 'full' (solid square).
Is it supposed to work better than this? dme.