I have a Xinerama (resp. Twinview) setup with two monitors. The metacity placement policy produces inpredictable and sometimes annoying results. I found the manual placement patch from http://intgat.tigress.co.uk/rmy/metacity/index.html to be exactly what I want. The patch allows enabling using gconf. It would be very useful to include this patch in the default metacity package.
Oops, that wasn't the patch I meant. This is it: http://www.vislab.uq.edu.au/research/accessgrid/software/fedora/related It places the new window on the screen, that the mouse is currently in.
This patch should be submitted to the upstream project for consideration. I am not necessarily opposed to the idea, but it's really upstream's call. Note that setting "disable_workarounds" to true has significant problems in practice, so we are not going to do that.