The weld seam has a simillar strength to glued one. It also means that no more toxic glues and adhesives should be used to bond wooden parts.
Here is video presentation of wood welding :
This technology could be used in 3d printing in same way some industrial metal printers use sheet lamination induced by ultrasonic vibration. It could be also used in FDM as the same process could be used to "melt" the wood and extrude it in layers.
Here are several links to more articles and papers about it:
Austrian company that already extrudes wood mass:
|Two pieces of wood with welding seam from friction welding|