The Interpolation From Curve Mapping node was renamed to Curve Interpolation. The node now support caching of interpolation for tremendously faster if it has to be evaluated very often. Below is a curve interpolation with and without cache option.
This newly added node mixes between two interpolation using one of two algorithms. Overlay which simply overlay both interpolation where zero means the first interpolation and 1 means the second. Chain which stack input interpolations beside each others.
This newly added node inverts the interpolation and possibly combine it with the original if chain was checked.