[Web-SIG] Could WSGI handle Asynchronous response?

[est]

I am writing a small 'comet'-like app using flup, something like
this:

def myapp(environ, start_response):
    start_response('200 OK', [('Content-Type', 'text/plain')])
    return ['Flup works!\n']        <-------------Could this be part
of response output? Could I time.sleep() for a while then write other
outputs?


if __name__ == '__main__':
    from flup.server.fcgi import WSGIServer
    WSGIServer(myapp, multiplexed=True, bindAddress=('0.0.0.0',
8888)).run()


So is WSGI really synchronous? How can I handle asynchronous outputs
with flup/WSGI ?