[wp-hackers] WP 2.5 gallery breaking xhtml 1.0

[Benedict Eastaugh]

I presume the thought behind it was to make it newbie-friendly and
reduce the number of people saying "Oh no, my images don't look like
they do on Matt's blog! WordPress is broken!" just because their theme
hadn't been updated with styles for the gallery markup. This kind of
issue would have been especially prevalent when 2.5 was first
released, since I imagine the number of theme authors who update their
theme as new features go into trunk is pretty small.