Our son, a LHP, is moving from high school (where he trhew about 65 innings) to a major D1 in the Fall - hopefully to contribute right away. He is pitching once a week for a summer team, and conditioning 3 days a week (and also going out with friends and enjoying his summer), but if anyone has been down this road, I'd enjoy hearing your thoughts.

You have to be prepared that your son has about a 10-15% chance of seeing any time on the mound. A major D1 if they are winning easily may give him a chance with a short leash.
If he is a 90+ guy he may get more chances than those who don't.

literly, tell him to be prepared to work out at least 4 times as much as he is currently. Be prepared to lift in the morning, throw during the day, and run in the evening.

Brod, here is a fall calendar I used at a D3 college 6 years ago. As you can see, there were baseball related activities 6 days out of the week. I would expect the D1 schedule to be even more intense. His life will be academics and baseball, not necessarily in that order.

http://www.maxxtraining.com/2001-02FallCalender.htm