Version: (using KDE 4.3.3) Installed from: Ubuntu Packages Most "normal" people are used to time being displayed in the 12 hour AM/PM format, not the 24 hour format which is considered by "normal" people to be military time. The current default in KDE 4 if the 24 hour format. This is always one of the first things I change on a fresh KDE profile. It's not a big deal for me when I setup a PC with KDE on it for someone else, but a "normal" person installing a KDE distro like Kubuntu for him or herself doesn't know exactly where this setting is like I do (It's in System Settings->Regional & Language->Time & Dates). It's not a huge deal, just a user friendliness thing. I love KDE4 and I think it is a fantastic desktop environment that is far and above the competition, especially Gnome, but if we want to win over new users then we need better defaults.
The defaults are based on the national standards for each country, if there is a specific country you think the defaults are wrong for you need to more detailed, however it's unlikely I'll change a default from the national standard. Choosing 12 hour clock in System Settings or the Plasma Clock can be made easier, they are both on my TODO list. One improvement already made that may help is defaulting to an intelligent default country rather than default to C and waiting for the user to choose a country. So users in 12 hour clock standard countries should see it immediately without having to change their country.
I'm in the US so I guess you should make it the default for the US if it isn't already. Is there anyway you can automatically pick the right country, by time zone or public IP or something?
The default format for the US is correctly set to AM/PM, so if the country is set to US then you should get the right format. The KDE default of 24hr time if a country isn't set can't be changed as the vast majority of countries use it and most locale files assume the default rather than explicitly repeating it. As I mentioned above, from KDE 4.5.2 onwards KDE will default the country to the system default, i.e. what you set during the system installation, so most new users should now get their correct formats without having to visit System Settings. Automatically defaulting the locale to current geographical location is not a good idea as not all users want the same locale as where they are currently located, but it is in our plans to respond to location changes and ask the user if they want to change locales / timezones / etc, but that's awaiting the introduction of a standard geolocation service.