An interesting article from CCRC about unresolved cybercrimes. The last three are from 2008, so it may be a bit early to say the offenders have not been tracked down, although as with any type of forensics, time is of the essence. "The 10 Most Mysterious Cyber Crimes" http://www.crime-research.org/news/26.09.2008/3597/ (27 September 2008)
Overall, the article highlights the main difficulty of cybercrime: tracking down the authors.
Comp. with "Cybercrime expert to educate MSU engineers on "Gen Next Terror" "(23 September 2008)
See in comparison "Second TJX hacker pleads guilty" (24 Septembre 2008) and the track for Palin's hacker which seems quite disproportionate in comparison with more damaging cybercrimes that just this one, "FBI Closing In On Palin Hacker " (22 September 2008)
"FBI on the trail of hackers after Palin's emails made public" (The Guardian, 19 September 2008)
and for statistics by DOJ (US) in september 2008