Yes, open JDK8 is reference implementation for JAVA SE8.
The official
Reference Implementations for Java SE 8 (JSR 337) are based solely
upon open-source code available from the JDK 8 Project in the OpenJDK
Community. Binaries are provided for both the Linux x64 and Windows
i586 platforms and Compact Profiles for Linux i586.
The binaries are available under two different licenses: The GNU
General Public License version 2, with the Classpath Exception and the
Oracle Binary Code License . For a given platform the binaries under
different licenses are built from exactly the same source code and are
functionally equivalent; the only real difference is the license
itself. Which license you choose will depend upon your particular
business and legal requirements.
Source: http://jdk.java.net/java-se-ri/8