To followup on my initial post, I've now managed to build calibre on my DNS-323. Its then a simple case to write cron scripts (which uses ebook-convert, calibre-smtp and calibredb ) to create periodicals overnight and send them to my kindle via wispernet. Nice :-)
If anyone is interested my (fun-plug based) builds are available here
http://www.plord.co.uk/funplug/0.5/
See also
http://wiki.dns323.info/
Pete