I just updated my server to Debian Lenny, which was released on February 14th.
So far, the only issue seems to have been my WordPress installation. I was getting errors in the Apache error log that the wordpress.wp_terms table didn’t exist in the database. I had to manually browse to /wp-admin/upgrade.php to do a database upgrade. After this, everything worked as normal.
So, if you come across a WordPress blog with no posts, no categories, and saying “Nothing to display for this category”, be kind and go /wp-admin/upgrade.php for them and run the database upgrade.
Thanks to this post on Erik Osterman’s blog for pointing out the issue.