Recruiting the Best
Rajesh points to Joels' post on Recruiting the Best.
It's because of this phenomenon—the fact that many of the great people are never on the job market—that we are so aggressive about hiring summer interns. This may be the last time these kids ever show up on the open market.
I believe in something similar in the MBA market. If you are good and have made the right networking moves and know your passion you may not be in job market after all for a long time and campus placements are a plus (not the only choice).