Some plates still out there. Vist, EPB and Hangl/Salomon are the most common. More than systems, it's modern ski design that's responsible for their demise. The shock absorption is still useful, but the stiffening of the ski that resulted from some older plates is pretty detrimental to performance.
The new Hangl/Salomon Lab ZZ plate is sweet, and works extremely well with modern short/soft skis.