'Seaside' is a Smalltalk framework for what might be called "Modal Web Development" or "Synchronous Web Programming", or even "Continuation Based Web Apps".
http://www.beta4.com/seaside2/
Very sexy it looks too. And it seems to be generating a lot of interest - Ruby and Java variants have already sprung up:
http://rubyforge.org/projects/borges/ http://lakeshore.sourceforge.net/
I googled for the python spin-off but didn't find one. Closest I found was Imposter (http://csoki.ki.iif.hu/~vitezg/impostor/) which looks like an earlier, partially failed attempt to do what Seaside now seems to be delivering.
Anyway, I guess all I'm doing is drawing this to the community's attention. Sophisticated web applications seems to be one of Python's key domains and this looks a significant new development in the area.
-- Mike -- http://mail.python.org/mailman/listinfo/python-list