Java 8 is not yet available from the main Java site (java.com), because it’s officially still in the developer testing/acceptance phase. The current end-user version of Java is Version 7 Update 67.
However, you can download Java 8 from the Oracle web site.
The latest version of Java 8 is Version 8 Update 20. It was made available on the Oracle site on September 18. Java 8u20 contains some new features, and fixes numerous bugs, including several security vulnerabilities.
Of particular interest to system administrators is the new Java 8 Advanced Management Console, which includes several tools that should make it easier to monitor and understand Java client systems.