The COLLADA 1.5.0 specification has been ratified by The Khronos Group and is now available for download:
The COLLADA 1.5.0 schema introduces new B-rep, kinematic, and OpenGL ES 2.0 effects feature support. The new 1.5 schema defining the COLLADA 1.5 XML Schema Namespace is a separate namespace then the stable 1.4 version and existing 1.4 instance documents will continue to validate. The COLLADA 1.5 schema is not backward compatible with 1.4.
Please report any issues regarding the specification or schema to the Khronos Issue Tracker.