I've been using django-sphinx (and Sphinx Search) on a few projects.
At my full-time job, I use django-sphinx as a replacement for the
admin search and Lucene to run the main app itself (I work at
Geodelic, and we're making the Sherpa app for T-Mobile's myTouch). On
our DB, I believe Sphinx beats out Lucene for indexing speed.
I haven't had enough exposure to Lucene to give it a fair shake, but I
do like Sphinx quite a bit. Unfortunately, django-sphinx can be
confusing to get up and running due to its lack of documentation--this
is especially true if you're new to search engines in general. So on
my next project, I'd like to try Haystack (
http://haystacksearch.org/
-- better docs, maybe closer integration with Django) + Sphinx if (1)
Haystack adds Sphinx support by that time or (2) I can build it myself.
Brian