“We shy away from using the term “events” because we don’t feel it’s very appropriate for the scope of activity we’re trying to capture. While our users may be interested in posting more formal, organized parties and whatnot to Plancast (and we certainly encourage them to), we want them to also feel completely comfortable sharing more informal plans (getting drinks, seeing a movie, going to the zoo, traveling to new york for a week, attending a conference, etc)."
http://techcrunch.com/2009/11/30/plancast/
I wouldn't be surprised if you had read that TechCrunch article. I once woke up with what I thought was a great original idea only to realize after some searching that it was exactly like startup I had read about on TechCrunch a couple months earlier.