At the calendar settings, for the Show holidays, Show birthdays, Show events, which I had chosen In calendar only or Never, the holidays, upcoming birthday, and upcoming event still shown at the board index calendar section.
Verified and reported. For team reference this bug is 0001776
I noted this bug as well yesterday and made a topic for it "smf 2.x support".
When it seemed to be a real bug instead of an error on my side, I asked a moderator to move my topic to "Bugs Reports" but that is not done yet.
JayBachatero has posted a temporary workaround in my topic that fixed the problem for me.
See: [SMF 2.0 Beta 3 Public] Calender items on boardindex (http://www.simplemachines.org/community/index.php?topic=229354.msg1473884#msg1473884)