Michiko Kakutani does a terrific job channeling Miss Piggy. Her review of “Summer Crossing,” Truman Capote’s recently dug-up first novel, has all the insouciant vocal tics and mannerisms that made Miss Piggy so truly, truly je ne sais quoi. Who knew Kakutani was such a great ventriloquist? She’d like us to believe it’s Holly speaking, which is pretty clever — and entertaining, too. And we went for it, except that Miss Piggy kept wiggling out, as usual trying to hog the spotlight.