I move to bless mod_wsgi's definition of WSGI 1.1  as the official definition of WSGI 1.1, which describes how to implement WSGI adapters for both Python 2.x and 3.x. It may not be perfect, but, it's been implemented twice, and seems ot have no fatal flaws (it doesn't do any lossy transforms, so any issues are irritations at worst). The basis for this definition is also described in the "WSGI 1.0 Ammendments"  page.
agree, disagree etc below
The definitions as they stand are clear enough to understand and implement, but not currently in spec-worthy language. (e.g. it says "should" and "may" in a colloquial fashion, but actually means MUST in some places and SHOULD in others, as defined by RFC 2119)
Thus, I'd like to suggest that Graham (if he's willing?) should reformat the "Definition"/"Ammendments" as an actual diff against the current PEP 333. Then, I will recommend adopting that document as an actual standard WSGI 1.1, to replace PEP 333.
This discussion has gone on long enough, and it doesn't really matter as much to have the perfect API, as it does to have a standard.