IMHO

1) It should check all predicates.
2) It should return a list of ready conditions.
3) It should *not* accept a list of conditions.
4) from_condition() should be removed.

Also notify() should try again if releasing a waiter raises RuntimeError because it has already been released.  Otherwise notify() can be a noop even when there are threads waiting on the condition.

I would also put

    for cond in conditions:
	cond._remove_waiter(waiter)

in wait_for_any() in to a finally clause in case the wait was interrupted by KeyboardInterrupt.  (Accounting for KeyboardInterrupt everywhere is not feasible, but for blocking calls which can be interrupted I think we should try.)