One of my older programs stripped datestamps in its input of a mysterious "-0400" string. According to the comments, I thought this was the timezone offset, but wasn't sure. Now I know a little more.
Thankfully I didn't write the code to assume that the offset was always -0400, so it's worked seamlessly through several daylight saving time changes. But some time recently, somebody reconfigured the machine generating the input to be on UTC time. Good idea, but now the offset is +0000, and the code broke.
I don't usually have to think about writing code for the other hemisphere, but in this case it might have helped.
(What would've helped more would've been to use Oracle TIMESTAMPS with time zones to store the data rather than throwing that part away. But I suspect nobody cares at this point in time but me.)
I actually work in UTC time myself. I deal with folks in the four primary continental U.S. timezones: Pacific, Mountain, Central, and Eastern. Having the times in UTC reminds me to always convert. And makes me look like a complete geek to everyone I know, which is good.