On OS X 10.7 Lion Java is not distributed with the operating system but is installed on demand. If you try to tun a Java task and Java has not yet been downloaded and installed you will receive an error stating:

No Java runtime present, requesting install.

If you are executing the task on your local machine then you will see a panel offering to install Java on demand. Click Install to download and install java. If the task is being executed on a remote machine then the panel will be displayed on that machine.