I got home last night, and the first thing I heard when I put on Baseball Tonight was "the big story out of New York" about Giambi meeting with Torre and Cashman to figure out what's wrong. Everyone's saying he has to go to the minors.
Giambi's clearly off to a poor start, but just to put it in perspective, here's the OPS's for some Yankees:

Giambi .711
Posada .709
Matsui .688
Womack .655
Bernie .603

Giambi's hitting better than half the lineup.
Some other pretty good hitters with a lower OPS than Giambi:
Durazo .708
M.Young .692
Loretta .686
Beltre .629
V.Mart .620
Lowell .587
Chavez .555

And looking back to last year, here are some OPS #s through May 10 of 2004:
Jeter .519
Huff .554
Ichiro .695

Boy, those guys sure were done.