<p>Could someone please explain to me how the current python webframworks fit together?</p>

<p>The three I've heard of are CherryPy, TurboGears and Pylons. However I'm confused because TurboGears seems to use CherryPy as the 'Controller' (although isn't CherryPy a framework in in it's own right?), and TurbGears 2 is going to be built on top of Pylons (which I thought did the same thing?).</p>

There are more to it ofcourse.
Here's a comprehensive list and details!
Web Frameworks for Python
Extract from above link:
Popular Full-Stack Frameworks
A web application may use a
  combination of a base HTTP application
  server, a storage mechanism such as a
  database, a template engine, a request
  dispatcher, an authentication module
  and an AJAX toolkit. These can be
  individual components or be provided
  together in a high-level framework.
These are the most popular high-level
  frameworks. Many of them include
  components listed on the WebComponents
  page.
Django
(1.0 Released 2008-09-03) a
  high-level Python Web framework that
  encourages rapid development and
  clean, pragmatic design
Pylons
(0.9.6.2 Released 2008-05-28) a
  lightweight Web framework emphasizing
  flexibility and rapid development. It
  combines the very best ideas from the
  worlds of Ruby, Python and Perl,
  providing a structured but extremely
  flexible Python Web framework. It's
  also one of the first projects to
  leverage the emerging WSGI standard,
  which allows extensive re-use and
  flexibility but only if you need it.
  Out of the box, Pylons aims to make
  Web development fast, flexible and
  easy. Pylons is built on top of Paste
  (see below).
TurboGears
(1.0.4.4 Released
  2008-03-07) the rapid Web development
  megaframework you've been looking for.
  Combines
CherryPy
, Kid, SQLObject and
MochiKit
. After reviewing the website
  check out:
QuickStart Manual
web2py
(currently version 1.43)
  Everything in one package with no
  dependencies. Development, deployment,
  debugging, testing, database
  administration and maintenance of
  applications can be done via the
  provided web interface. web2py has no
  configuration files, requires no
  installation, can run off a USB drive.
  web2py uses Python for the Model, the
  Views and the Controllers, has a
  built-in ticketing system to manage
  errors, an internationalization
  engine, works with MySQL, PostgreSQL,
  SQLite , Oracle, MSSQL and the Google
  App Engine via an ORM abstraction
  layer. web2py includes libraries to
  handle HTML/XML, RSS, ATOM, CSV, RTF,
  JSON, AJAX, XMLRPC, WIKI markup.
  Production ready, capable of
  upload/download of very large files,
  and always backward compatible.
Grok
(0.13 Released 2008-06-23) is
  built on the existing Zope 3
  libraries, but aims to provide an
  easier learning curve and a more agile
  development experience. It does this
  by placing an emphasis on convention
  over configuration and DRY (Don't
  Repeat Yourself).
Zope
(2.10.4 Released 2007-07-04,
  3.3.1 Released 2007-01-14, Zope 3.4.0c1 Released 2008-01-31) Being the grandaddy of Python web frameworks,
  Zope has grown into a family of
  frameworks over the years. Zope 1 was
  released in 1999. Zope 2 is both a web
  framework and a general purpose
  application server, today it is
  primarily used by
  ContentManagementSystems. Zope 3 is
  both a standalone framework and a
  collection of related libraries, which
  are also included with newer releases
  of Zope 2. All of the Zope frameworks
  include the ZODB, an object database
  for Python.