All the digital watches I've had have the option to show 12hr/24hr. Even the N900s stock clock has the option.

I like this little clock though, saves messing about in Queenbeecon widget. (totally no disrespect to those that prefer to use Qbcon, of course).

A few peeps over on the N900 FB page are wondering if a weather widget could be added to make it look like the HTC clock.