If your Google calendar ends up full of many different types of events (film nights, lunch dates, and doctor appointments, for example), there's now an easy way to categorize them using colors.
Just click on an event, then click the colored square in the top left of the pop-up bubble and pick a new color. If you don't see this option quite yet, hang tight -- it'll be there for everyone within the next day or so.
Only you and anyone else you have given edit access to your calendar will be able to see the colors you choose.
[Source: Gmail blog]