A few days ago the Department of Justice released a chart that digests all unsealed terrorism-related prosecutions that have taken place in federal courts from September 11, 2001 to March 18, 2010. The chart accompanies a letter from DoJ to the Senate Judiciary Committee which explains the effectiveness of prosecution under federal law on terrorist activities. It also highlights the fact that since 2001 the federal courts have produced 12 life sentences and 59 other sentences of over 10 years or more in terrorism-related cases. You can read the letter here and view the chart here.
These facts make the federal courts seem like a very effective tool in disrupting terrorist activities. According to the chart there have been 403 successful prosecutions of terrorism-related crimes in less than 9 years.