The HTML5 Test Suite Conformance Results page has now been updated to clarify the situation:
The HTML5 Test Suite Results aims to help implementers write applications that support HTML5. In no way are these conformance tests to be construed as providing certification or branding of HTML5 implementations. The only claim that could be made is that a particular implementation is conformant to a particular version of the HTML5 Test Suite.
In other words: The results of these tests do not reflect the general HTML5 compliance. They only show which browsers pass those specific tests available at that specific time.
It is inappropriate to cite those results as other than work in progress and unstable.
The page also explains that the Test Suite is under development. At the moment, there is a relatively small number of tests, but this will grow over time.