In an effort to not fall too far behind, I installed Xcode 4.3, which promptly trashed my
/Developerdirectory (not a bad thing, really). Homebrew was supposedly updated to cope, but when I tried to
brew install graphviztoday, it complained about not finding the developer directory there.
I was able to convince graphviz to install without resorting to symlink-ing, using the following incantation:
sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/