Qt-wise, the packages are self-contained, that is, they already include the Qt 4.8 framework they were linked against. You only need to additionally install the SDL framework (1.2.15+), which is required for MAME anyway on that platform. The binaries require Mac OS X 10.5 or higher.
If you want or need to build QMC2 from source, please follow this FAQ!
Builds of development versions:
David Ely maintains the Mac OS X builds; he also keeps official releases and builds of recent SVN revisions on his server.