Give the gift of Drupal. All merchandise is 50% off through 2016.
I created support for all-day events.
To use this thing, it's required to configure the date field to day-month-year granularity only (no minute, second, hour!). So you can only have all-day events for the field, it needs to be improved in the future, for example having an all-day checkbox.
You also need to patch date module as well.