Picture this scenario:
One of the dozen or so people who live outside the US reads
slashdot until he leaves work at 8pm. He gets back in to work at
9am the next morning to find a completely new front page with
several stories that he _hasn't seen_ relegated to 'yesterday's'
People with different, particularly 12 hour out of phase timezones
need a different today borderline so that they have a reasonable
chance of seeing new articles on the front page. Possibly at least
one or two of those dozen outside the US probably even work only
a normal 9-5 day.
It couldn't possible be a load problem since only a dozen people
outside the US read slashdot (main consumer) and are thus
affected by this bug.
This could probably be based on timezone setting...