After running into problems installing flood with Macports, specifically:
Error: db46 requires the Java for Mac OS X development headers. Error: Download the Java Developer Package from: <https://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wa/getSoftware?bundleID=20719> Error: Target org.macports.configure returned: missing Java headers
I had already installed this!
The solution was to create a symbolic link to the installed files, so Macports could find them:
sudo ln -s /Developer/SDKs/MacOSX10.6.sdk/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Headers /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Headers