If you're going to go, I'd suggest going at night and keeping a low profile. I haven't been in the past five years or so, so it's possible security has tightened, but it was manageable the last time I went. There was a single floodlight and a truck parked near it, but it seemed to be part of a mulching project going on with some of the trees. I've heard stories of people getting arrested, but there wasn't (at least back then) any kind of outpost for security to set up in. It's also extremely easy to just bail into the woods if someone comes along. Just have an exit plan.

Also, be careful because two of the bigger, interconnected buildings have a lot of asbestos, so don't go in without a high quality respirator. Those buildings are marked though.

If you're willing to take the risk and go late at night, it's a fascinating campus to explore. Just be cautious. :)

Holy shit, I was in the bus when this happened and had no idea why it stopped blocking the entire street for a couple of minutes. Mf really just got back in and continued on like nothing had happened.