Through my career the college interview calendar has been pushing back. In the mists of time before the Y2K bug, new grads started interviewing in the spring and if they were on the ball locked down a job in March, for a June start date, three months lead time. As big companies developed an insatiable hunger for new grads, starting I think with Microsoft but exemplified by Google, they were willing to make offers earlier and earlier. The fall career fairs, originally for those graduating in January, became a place to make full time offers for next June, and the spring fairs were mostly for picking up interns. Then the insatiable hunger spread to internships and now most hiring happens in the fall, nine months before the start date.
This does everyone a vast disservice. Small companies can't hire new grads effectively because they cannot wait nine months for a new employee. College students are forced to make a major life decision unnaturally early. Big companies hire students into general new grad piles and them sort them out later, eliminating one of the most important steps of hiring - meet your new boss before you decide.
There might be a light at the end of the tunnel though - in the past year questions about reneging on job or internship offers on advice sites has gone from basically zero to a pretty regular occurrence. Personally I think a significant amount of reneging would be a good thing so that companies pull back their offer windows to something merely extended as opposed to downright ridiculous.