As Kooshie had stated, the Droid X can support several calendars and even allows the option online to color code them(through Gmail).
The common supported calendar types would be either:
Gmail Calendars (iCal)
You can also import an iCal to Google Calendar for additional calendars. The marketplace may have additional calendar options.
I have a couple of calendars loaded into my google calendar. However I haven't figured out how to get the color to be different for all of them. Can you post the steps to get that part to work?
Once you have logged into your gmail calendar from a PC, look where it shows all your available calendars on the left side of the screen. Each calendar should have a little downard pointing triangle beside it. Click that triangle and a screen should pop up that shows several choices (Display only this calendar, Hide Calendar from list, Calendar settings, etc). Below that should be a grid of several colors. Click on the color you want and your calendar should change to that one.
I know that Android 2.1 only allowed the calendar from your main Google email account to synchronize (this was resolved in 2.2 and has worked on the HTC Incredible, Droid X and Samsung Fascinate that I have owned). I honestly cannot remember if the individual colors showed up on the main gmail account calendar under 2.1 or not.
I set up 3 calendars in my google account, US Holidays ,Phases of the moon and a caledar that has a recurring event on my Droid X in month mode I can only see the recuring event in agenda mode I can only see recurring event but not moon phases, are you saying you can see moon phases on your phone calendar?