Cron jobs seem to be run on UTC rather than local time. This isn't an issue for most people, but for people like me, who have cron jobs that have publicly visible effects, this is a problem. For example, my site uses a cron job to make a chat room visible at a specific time every week. I forgot to adjust the cron job last week and all of our visitors got a "permission denied" error.
This issue also affects anyone who uses the following:
The Cron Entries will need to be adjusted twice a year if your server is in a timezone that uses daylight savings time.