Eclipse OCL is an Open Source project. The original code for OCL 1.x was contributed by IBM. It has evolved to support OCL 2.x under the auspices of Eclipse.
There is now a significant personnel and corporate overlap between the Eclipse OCL committers and the OMG OCL RTF and so Eclipse OCL is pioneering solutions to many of the under-specification problems in the OCL specification.
You can expect future changes in OMG OCL to have an implementation in Eclipse OCL to demonstrate their viability. It is likely that the next version of the OCL specification will use Eclipse OCL and M2T(Model to Text) tooling to eliminate inconsistencies. Eclipse OCL is currently in use to check that the OCL used in the UML 2.5 specification is syntactically and semantically correct.
Direct tooling of the UML 2.5 and OCL 2.5 specifications for the Kepler Eclipse release may demonstrate that the OCL aspects of the specifications is also functionally consistent.