Waaaaaaaaaaaahh!! 
I wish they would do a re-run!
Jeff, who do I have to call to demand a re-run? 
argh!
So, tell me what happened, pleease .. 
It's one of those typical twisty-turny kinds of plots. You really do have to see it. Turns out Grissom had somehow not told Katherine he was leaving on sabbatical until the day before he was leaving. She had, like, 24 hours to convict a perp, who just got acquitted of murder, of another, earlier murder--and in the process she proved that someone else had been wrongfully convicted and imprisoned for murder. Katherine will be in charge administratively while Grissom is away, but Warrick is the "rock" of the team, whether he knows it or not--so Grissom says. Nicky was betting that Grissom won't be back, and Grissom had to tell him (Nicky) to stop hugging him (Grissom). Grissom advised Greg to get his own lawyer through their union and not rely on the department's lawyer. Sara did not look pleased at the end. Alan Rosenberg, Marg Helgenberger's husband, did a repeat turn as an attorney.
And at the very end--OK, here's the spolier question, but you asked for it--it looked to me like just after Grissom left the office, a package was delivered to his desk--containing another model of a crime scene?
