Several of the folks I know, including Joel and the SharePoint Product Team started posting "calendars" as text in a blog post. That was entertaining because I was just getting ready to do the same thing to talk about the conferences I'd be at and the presentations I'd be giving. However, I realized that we've got the same problem with calendars as we have with most content, it's scattered all over the internet. So I created a SharePoint Calendar that has all of the major events that I could find. I've added an email alias calendar@thorprojects.com that you can send requests for calendar updates to. (My assistant will process these for now, if we get enough activity I'll automate the system.)

Once we get a few people linking to their entries in the calendar I'll put a web part on the page that will provide a set of links to pages linking to the event (so you can see who's presenting what at the event)

With a little luck we'll end up with one calendar for SharePoint stuff.