My trying out WordPress 3.0 in advance of its final release has brought me errors on the links management page. After a spot of poking around the TRAC, I found that the bug already has been reported and that the cause is an extraneous column in the *_links table called link_category. The change in taxonomy handling over the years seems to have made it redundant so I removed the said column from the database using a command like the following from both the MySQL command line and MySQL Query Browser:
alter table wordpress.wp_links drop link_category;
That seems to have made those errors go away and I hop that their upgrade code takes care of this before WordPress 3.0 is let loose of the general blogging public. Taking out the coding brittleness would do too.