Pretty much what Hurracane said, ECX isn't an offical ESF mod created by the ESF team and was released quite some time ago. All the latest trailers you have seen recently are for the final offical version of the Mod called ESF: Final. This look awesome and has no release date, but thats no big deal as you can still enjoy ESF 1.2.3 or some of the unoffical add-ons like ECX RC2.