Not all samples have been approved by HL7 Example Task Force, so check out the http://wiki.hl7.org/index.php?title=CDA_Example_Task_Force for current status.
The reason why we include complete files above is so that we can validate the XML using industry standard tools, such as the NIST TT Validator.
Lots of people have implemented C-CDA and it's the primary document standard in MU2 and now MU3. (Note: if you'd like to submit a public sample, shcek@ https://github.com/chb/sample_ccdas)
Samples posted here may not been approved by HL7 or any other body. They are educated guesses