Based on discussion with Richard Bair & Michael Heinrichs (and approved by both), for the 2.1 we will introduce only this:

FXCollections.observableList(List<E> list, Callback<E, Observable[]>
extractor);
FXCollections.observableArrayList(Callback<E, Observable[]> extractor);

These lists will fire update notifications if some of the Observables
extracted from the elements will change.
For this, we will need a new method in ListChangeListener.Change:

public boolean wasUpdated()

returning false by default (cannot make it abstract now).

BaseObservableList + invalidation() methods will be defered to some
later release.