As a veteran of the premature standardization trenches (I wrote most of the ISO/IEC 14772-1 "VRML97" specification before I changed my last name from "Bell" to "Andresen")... I agree with foreverdamaged. It is too early to try to create a formal specification.
However, it think writing informal specifications documenting how bitcoin works right now is a great idea, and will be really helpful when it is time to go through some standardization process.