Ahh, indeed this is a new compatibility bug with 2.3. I've checked in a fix to the SVN. You can check it out at:
svn co http://svn.codespaces.com/bluehousegroup/event_calendar
Otherwise, tomorrow I'll make another zip file with the latest build.
Sorry about that. Good thing 2.3 isn't an official release yet. Still have time to get it up to speed.