Datestamps are inserted with wrong value (about -4 hours)

SUMMARY:
When Datestamp values are inserted in the DB, it's not the same value as the input.

DETAILS:
I've added a Datestamp field to my story nodes. I'm accepting dates in this format: YYYY-MM-DD for every story.
If I input "2008/10/16", it displays this date exactly - no problem.
But in the database, in the content_type_story table, I get a UNIX timestamp value of 1224115200. If I convert that back to a normal date, I get the wrong date:
date("Y-m-d H:i:s", 1224115200);
returns: 2008-10-15 20:00:00

Which breaks my Calendar views, as all nodes appear on the previous day. I've set my site to UTC or EDT, same problem.

SOLUTION?
At this point, I don't really care how this can be fixed. Unless there's a settings error on my site, I'd just like to know where in the code the data gets inserted into the DB - I will manually add ~4 hours to every date. I've looked through the code but I could not find it.

Does it have something to do with the timezone or local time on the server? Is it a PHP thing, a Linux thing, a CCK thing or a MySQL thing? As I said, I'm just looking for a quick hack to artificially increment all timestamps by 4 hours.