Well, only 24 hours since the signing of UFA Ilya Kovalchuk, the 17 year $102 million contract has been rejected by the NHL. The league has five days to review the contract, yet it only took one for the league to determine the contract circumvents the salary cap.
More will be reported soon but I'm sure the issue has to do with the sub $1 million years at the end of Kovy's contract. Other players in the league (Hossa, Richards, Pronger, Zetterberg, etc) have similarly structured front-loaded contracts but none of those players' salary dips below $1 million.
The NHLPA can file a grievance against the league's ruling within 5 days then an arbitrator will make the final decision.