According to the spec:

    wsgi.multithread	This value should evaluate true if the application object may be simultaneously invoked by another thread in the same process, and should evaluate false otherwise.

Tornado requests are all running in the same the same threads (this an event loop afterall). For gevent or eventlet the question is other. Should we consider that running in a greenlet change that setting. I guess gevent don't change it because afaik all greenlets are running in the same thread. It could be interresting to ask on the python ml maybe.