Similar (same?) problem with my website.
After the clocks changed yesterday, all of my ‘All Day Events’ have moved back 1 day – because 1 hour has been subtracted from the start/end times.
I have checked WP Timezone settings and they are correct for my location (UK, London).
This is really annoying – as checking earlier posts indicate it is not a new problem.
Are the developers working on this ?
I’m running version 1.8.2 and WP 3.4.2.