Thanks for the comments on recycling which give me more to ponder (especially helpful now that I have the time in which to do said pondering).
For my next trick, I have just been commissioned to do some work developing online policy discussion mechanisms. I am working up the detailed specification at the moment but am already thinking about the best framework on which to build this. I have been attracted to Plone as a mature and well-structured system. And it has the advantage of being easily installable onto a Mac for development purposes (and perhaps eventual running).
I have spent more time in the past on PHP/mySQL products (including the very fine WordPress which lies behind this blog. A move into Python would be challenging but it does seem to impose lower overheads than PHP and be altogether more concise.
Any ideas and experiences from anyone would be much appreciated as I explore the world of application servers and content management systems.