Point taken -- rather than breakage with wsgi:// (which I thought might be clean) I will look at subverting urllib2. The goal will be to produce a WSGI-compliant server interface into which any WSGI app can be plugged & played.
This is a good direction for twill, IMO, so I'm moderately enthusiastic about implementing it, too.
A few additional comments:
zope.testbrowser looks nice, but it's unclear to me what the compelling advantage is. I've got to look at it more before I make my life more complicated by trying to switch to it... ;)
the twill API doesn't provide direct access to anything mechanize-tic, but the full mechanize interface is of course accessible to extension functions, which are just Python (of course!).
Finally, even if twill becomes WSGI-aware, writing the tests is going to be a huge pain. (Hmm, maybe if I get the BickingBot entangled in twill he'll write a WSGI recorder!)
Simple (but working) implementation of in-process testing with twill: <a href="http://www.advogato.org/person/titus/diary.html?start=119">discussed here</a>.