To me, it's a little odd that HL7 requires you to be a member to distribute the standard within your organization and in that sense implement the standard and tell others who have implemented the standard what parts you'll be implementing, especially when it's nothing classier than a few pipes and carets for 2.x and some sort of XML for 3.0.
I can understand paying money to use a library to utilize HL7 or even the source code to build the library to utilize HL7. But what's the point of requiring membership to see the spec to write the sourcecode to build the library to utilize HL7?