Update on 12/30/2009:
The Google Hindu Calendar linked and described in this post has been renamed as Google Hindu Calendar - MST, for Mountain Standard Timezone of USA.
If you have a Google account, you can add this Google Hindu Calendar - MST to your Google account using this link: Add Google Hindu Calendar.
To simply view the calendar in your web browser use this link: View Google Hindu Calendar. After viewing, if you want to add this Google Hindu Calendar - MST to your Google account, there is a button at the bottom-right corner of the screen.
For calendars of other timezones, visit this link: Google Hindu Calendar with Timezones.
Original Post below:
Google Calendar was released on April 13th, 2006. This is a few days later than April 1st, on which date Google traditionally launches new products. More information: Google Calendar Overview.
I have created a Hindu Calendar on Google Calendar. This calendar is publicly shared. Just search for "Hindu Calendar" in Google's public calendar search and look for Hindu Calendar / Panchangam by A S. Click on the "Add Calendar" button to access it.
With this, you can easily access the important Hindu calendar information about each day. As of today, the calendar has only information about important Hindu festivals from April to December 2006. There is a little more information for the month of April (such as amAvAsya, pUrNima, ekAdashi, sankatahara chaturthi, etc.). In the coming days, I will be adding as much information as I can from the Hindu Panchangam.
This will be an ongoing effort. Until some professional Panchangam maker like Kalnirnay publishes in the iCal format, updating the Google Hindu Calendar will be a manual effort. As such, I need help in entering information into this calendar. If you would like to help, please write to my Google mail id libranlover.
Hope this calendar will be useful for everyone, all over the world. As the Google Calendar application grows rich with additional functionality, this Hindu Calendar will grow in tandem, with more features and lots of useful information.
I wish Google would provide an easy link / URL for the calendar, by which it could be shared and accessed by everyone. Until Google provides such an easy URL, the easy ways to access a particular calendar is to be invited by the calendar's owner or to search for public calendars. Meanwhile, here are a couple of links to the Hindu Calendar, if you can figure out how to use them:
Hindu Calendar iCal address
Hindu Calendar XML feed.