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