Resources- obviously ZF Documentation :)
1. "Zend_Date":
2. "Zend_Locale_Date":

And short example of using Zend_Date with Zend_Locale
[geshi lang=php]
// setting default timezone

// setting locale according to users`s browser
$locale = new Zend_Locale(Zend_Locale::BROWSER);
// creating Zend_Date object AND passing locale object
$date = new Zend_Date('2008-11-03 18:34:40',null,$locale);
// outputting date with given format
echo $date->toString('EEEE, d MMMM YYYY');
For polish the output will be: "poniedziałek, 3 listopada 2008, 18:34" and for Dutch: "maandag, 3 november 2008, 18:34"
The coolest part is that Zend_Locale supplies your app not only with localized names of months, years, and so on, but also with bunch of date formats widely used in different countries :)