Fixed, along with a couple of other minor annoyances.

Changes have been made in Git (master):

commit fca899cecfd8c8cf8a549d6fdd183e1068307808
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Fri Aug 30 14:47:27 2013 -0400

     Bug: 12630 Must set timezone on exceptionoriginaldate too.

  kronolith/lib/Event/Sql.php |    1 +
  1 files changed, 1 insertions(+), 0 deletions(-)

http://git.horde.org/horde-git/-/commit/fca899cecfd8c8cf8a549d6fdd183e1068307808

Changes have been made in Git (master):

commit 9baec448125219a70647cbaaefc9d319320d9f08
Author: Thomas Jarosch <thomas.jarosch@intra2net.com>
Date:   Wed Aug 28 00:57:45 2013 +0200

     ActiveSync import: Fix timezones for exceptions of recurring all 
day events

     Without this fix we add the exception
     for the event on the wrong day.

     Bug 12630

     Signed-off-by: Michael J Rubinsky <mrubinsk@horde.org>

  kronolith/lib/Event.php |   12 ++++++++----
  1 files changed, 8 insertions(+), 4 deletions(-)

http://git.horde.org/horde-git/-/commit/9baec448125219a70647cbaaefc9d319320d9f08

I think I found something more:

I create a weekly recurring event with ten occurences.
Then I pick one event on the PIM and move it to another day.

This creates a new event in kronolith. If I open that event,
the text say something like "This is an exception for the original 
event on DD:DD 22:00H".
-> The timezone for that text is missing / wrong.

When I now rename the title of the exception event and sync the iPad,
the event vanishes on the iPad. Oops :) More tomorrow.

ActiveSync import: Fix timezones for exceptions of recurring all day events

Without this fix we add the exception
for the event on the wrong day.