This should build on OS X. Use homebrew to install deps & this command:

Within src directory:

    make USE_UPNP=1 -j $(sysctl -n hw.ncpu) -f Makefile.osx all
Merge branch 'namecoinq' into macosx
Macro guards to make it compile on non-clang compilers.
Switched to Berkeley DB 4. Other changes (see details below!!!)

- got rid of gthread
+ removed a bunch of unused and irrelevant-to-osx stuff from Makefile
+ no need to specify `USE_UPNP=1`, it is done for you (make sure to install it!)

Instructions:

1. `brew install openssl berkeley-db4 boost miniupnpc`
2. cd src && make -f Makefile.osx -j $(sysctl -n hw.ncpu) all
Bloody MSG_NOSIGNAL defines for linux/mac/win compat.

Thanks for pointing it out @luke-jr!
Fix last breaking change on linux. Now compiles (at least with clang :P)
Merge pull request #136 from okTurtles/macosx

Minimal changes to get building on OS X with clang and Homebrew