These are Homebrew formulae for mspgcc, the compiler toolchain for the MSP430 microcontroller. The repository includes binutils, gcc, libc, and the mcu files.
To get everything, type:
$ brew tap sampsyo/mspgcc
$ brew install msp430-libc
Since libc is the top of the dependency chain, this should suffice to get everything you need.
$ msp430-gcc --version
msp430-gcc (GCC) 4.6.3 20120301 (mspgcc LTS 20120406 unpatched)
...
These formulae are quick n' dirty and undoubtedly need some improvement (missing dependencies, brittle workarounds, etc.). I also haven't (yet) included gdb or mspdebug.
One manual step is required to get a working system. Annoyingly, since the --prefix= compile option for each of these packages is different, each of the various tools can't find required files installed by other packages. To consolidate the various lib pieces under a common directory, run:
$ ./addlinks.sh
This script symlinks everything from all the packages into msp430 under the msp430-gcc keg. This means your root for the MSP430 toolchain is something like /usr/local/opt/msp430-gcc/msp430 (which would be /usr/local/msp430 on a "normal" installation).