The ArmA2 "Beta" is required to run, and host, DayZ.
The latest beta however is not required (and hasn't been for quite a few beta releases). It hasn't mattered much if server hosts updated their beta versions, as clients on older versions could still connect.
It seems a lot of DayZ server owners have already just recently upgraded to 94876, essentially turning their servers into ARMA2 1.61 servers. This was not necessary as far as I know. Of course this means every ARMA2 player out there who wants to play DayZ today onwards, will need to upgrade to the latest beta.
They won't be able to play on vanilla ARMA2 servers either with the beta, unless those servers also quickly update to 1.61 right?