The Twisted community has decided it's time to clean up its web act. The problem for a while has been that there were three "competing" packages that might have formed the basis of any web application: twisted.web, nevow and twisted.web2.
Now they have decided that twisted.web is the right namespace, and the immediate plan is to backport the stable functionality from web2 and the nevow application server into twisted.web, giving a more advanced set of web functionality in a way that offers best compatibility to existing users. Nevow will intially remain, as a pure templating solution, but there's a possibility that functionality might also be repositioned eventually.
This has the smell of a compromise, but as compromises go (and as you'd expect in the Twisted world) it seems to be a pragmatic engineering solution to the current rather confusing situation.