I've created a Perl Community calendar on Google Calendars. I've wanted to do this sort of thing for a long time to help track that stuff for The Perl Review's print listing. I've given up on writing my own calendar application. Google Calendar has a decent interface that I don't have to support, and it provides feeds: XML, iCal, and HTML.
I'll do some more work to make nice URLs and so on, but for now it's there. I can add people as editors, although I expect that as with anything in the community, there will be a couple of people looking for the events and entering them.
I don't want to make a lot of work for people organizing conferences, so just make sure I know about the event so I can add them (which really means post them to use.Perl as a story for the front page). I'll pull from the events in the calendar for that section in TPR.
There are some other online calendars for Perl too. Most notably is the one for the Lisbon Perl Mongers. Many other Perl Mongers groups have calendars too. If you know of any others, please let me know. I'd like to devise some sort of aggregator to merge things into a single calendar.