Third parties have been examining the GEDCOM X code since it was revealed in 2011.
FamilySearch opened up the GEDCOM X site during RootsTech 2012.
FamilySearch had no product, and no third party had hurried to support it,
so at that time, there was no single product that supported it.
Right now (2012 Dec 1), there still seems to be no application that reads GEDCOM X files yet. There is at least one utility that writes GEDCOM X files, but that is merely FamilySearch's own GEDCOM to GEDCOM X Converter, which was introduced in June of 2012.
That finally enabled a first look at the actual GEDCOM X file format.
FamilySearch has not released a GEDCOM X to GEDCOM converter yet.
Please note that, right now (2012 Dec 1), FamilySearch is still planning to use the GEDCOM X file format and API, but that FamilySearch is not actively using the GEDCOM X format yet.
In fact, the GEDCOM X specification is still not even at version 1.0 yet.
Third parties that might support the GEDCOM X format eventually are not very likely to do so until FamilySearch releases GEDCOM X version 1.0 and actively starts using it themselves.