Another All Black on the move is Daryl Gibson, the centre joining Glasgow Warriors after 28 Heineken Cup appearances for former double champions Leicester Tigers.
The Warriors have also added one of the world game's most exciting wings in Samoan international Lome Fa'atau.
The former Wellington Hurricanes star was the top scorer in the Super 14 last season with nine tries.
Jack and Gibson could find themselves in early confrontation when Glasgow travel
to Saracens in Round 1 while Biarritz Olympique Pays Basque are set to have a major
injection of South African talent headed by exciting wing Ashwin Willemse.
Capped 16 times by the Springboks going into the World Cup, he will link up with the
2006 Heineken Cup finalists after the World Cup and join fellow South Africans Pieter
Louw, the Western Province flanker, and young Cheetahs lock Izak van der Westhuizen at Parc des Sports Aguilera.
Biarritz start the Heineken Cup at Viadana, who supplied a trio of players - Josh Sole,
Kaine Robertson and Matias Aguero - to the Italian World Cup cause.