This was suggested and discussed by a number of members:
The thread "Calender of local events in Regional Gardening Threads" in
Site Talk forum
I have finished a beta version of this calendar of events. You can now add new events, view them, and see other events. This is a beta program so far, and it is missing most of the feature that I intend to add, so be aware of that! Future features will include a way to comment on events that have been posted, and ask questions about them and stuff like that. Also, I will soon have a better way to find them, by entering your zipcode and it'll pull up surrounding events. Until then you can simply view the full list in its entirety.
To view the calendar, go to the Goodies area (linked in the navigation on the left) and then click on "Gardening Calendar of Events" and you're off to the races.
I would be very grateful if interested parties would add a few events in their area. Once we have some data in the system, it'll make it much easier for me to program the next steps.
The direct link to the calendar is here:
http://garden.org/apps/events/