There is a carbon driver in 1.1.4 - you don't need to be using an X server to run MWF binaries (it is extremely alpha and undergoing a major rewrite in HEAD) but there are a couple gotchas:

1. It's not using the ATSUI font backend yet so you need to have X11 installed (because it gives us the ft2/fc deps)
2. You can't launch SWF/mono apps on mac with mono foo.exe

The solutions is (assuming swf-buttons as an example) to use macpack.

macpack is a tool installed with 1.1.4 to package a managed assembly as a OSX .app bundle; the usage for swf buttons would be

macpack -m:1 -n:swf-buttons -o:. -a:swf-buttons.exe

There is macpack --help and a manpage but I'll reiterate these options here

-m == --mode; the mode of macpack being either SWF or Cocoa#
-n == --name; the name of the .app bundle to output
-o == --output; where to output this bundle
-a == --assembly; which assembly to macpack

Information obtained from the mono-winforms mailing list.