Ask for a mentor.

You'll probably have a manager, but try to find someone one who's willing to take you under their wing, who understands the ins and outs of the department/org/corporation's politics, and understands not just how things are being done, but why they're being done.

Start out by doing most programmer's least favorite job -- documentation. You'll want to know the systems inside and out. (at my last job, I'm still remembered for labeling all of the systems ... of course, it was because I was frustrated with ejecting a cdrom, and then wandering around the data center trying to find the tray that was sticking out so I could find systems (which doesn't work when it's inside an cabinet, and the tray came out, hit the cabinet door, then went back in)).

The trick is to find the jobs that other people want done, but don't have time to do themselves... The types of things that would make their life easier, but they just don't have the time with their current schedule to get done. Unfortunately, finding those jobs can take some time to figure out what they are. (and if you're being brought in for a specific task, you probably don't have the luxury to work on).

Oh -- and don't spend the entire day chatting on websites.