Pretty harmless? I'll admit that I don't know much about this case, but this bit seems to indicate otherwise:

"Mr McKinnon admits that he hacked into 97 US computers from his bedroom in north London between 2001 and 2002 and left a message on one machine saying: "I will continue to disrupt at the highest levels.""

Two years, almost 100 computer systems, taunting and threats.. that doesn't sound so harmless to me.

[1] http://www.telegraph.co.uk/news/worldnews/northamerica/usa/5...