This report says “iPod touch software 1.1.2 adds calendar functions“:

Arriving alongside iPhone software version 1.1.2 on Thursday evening was iPod touch software version 1.1.2, which adds new calendar functionality to the touch-screen media players. Thus far, one of the only visible features delivered by the update appears to be the ability to add and edit calendar events through the Touch’s calendar application. Although these capabilities had long been available to iPhone users, Apple omitted them from the initial version of the Touch software presumably to help differentiate the player from the iPhone.

It still needs more capabilities, but this is a big improvement.