This article (which I found thanks to a link over at Bruce Schneier’s blog) is quite interesting. What exactly is “unauthorized” access, as far as computers are concerned?
If the answer seems clear-cut to you, you may want to read this article to see how the issue quickly becomes murky. As is often the case, old legal precedents don’t quite work when applied to new technology.
For more info on this subject, and some “historical” cases in the same sort of vein, see:
Remarks on Oregon vs. Schwartz
Computer or Crime? State of Oregon v. Randal Schwartz