These builds are created by the community for the community – they are experimental and are probably not stable.  Thanks Gildas and Henri for your work !

I downloaded the 64 bits version (32 bits version also available) and installed it in a couple of minutes.  These builds install in Apple proposed location : /Library/Java/JavaVirtualMachines

First test is obviously :

marsu:~ sst$ /Library/Java/JavaVirtualMachines/openjdk-1.7-x86_64/bin/java -version
openjdk version "1.7.0-internal"
OpenJDK Runtime Environment (build 1.7.0-internal-henri_2010_11_25_16_22-b00)
OpenJDK 64-Bit Server VM (build 20.0-b02, mixed mode)

Then I configured Netbeans to use that JDK to compile and run projects :

Netbeans 6.9 has build in modules to support some upcoming Java SE 7 syntax, such as the language simplifications proposed by project Coin.

BTW, should you want to create the builds yourself, everything is documented – you can even start a continuous build with Hudson. You can then download specific scripts to build OpenJDK on MacOSX and to create the installation packages (Will require Apple’s Developer Tools to be installed)

Enjoy !