Hi @sbj,Only 2 alternatives but not at this level right now @Lindal_Oronar .
AndyB's and Waindigo's calendars.
Andy's has now a sidebar widget for upcoming events, too. So if you just need basics, like a calendar, adding events through thread and showing events in sidebar, you can go with Andy's. Jon's (formerly Waindigo) has google calendar and ressources implementation but no sidebar widget yet and you can add events through thread, too.
Thanks for your answer.
I take a look at the 2 addons.