I wish the article's author had done a little bit of background work to find references to the CCC presenter's research.

Here is the paper published last year describing the research on fingerprinting. The second URL at uni-regensburg.de does not require an ACM account to download the paper.

Website fingerprinting: attacking popular privacy enhancing technologies with the multinomial naïve-bayes classifier
http://portal.acm.org/citation.cfm?doid=1655008.1655013
http://epub.uni-regensburg.de/11919/1/authorsversion-ccsw09....

Dominik Herrmann, University of Regensburg, Regensburg, Germany
Rolf Wendolsky, JonDos GmbH, Regensburg, Germany
Hannes Federrath, University of Regensburg, Regensburg, Germany

"Privacy enhancing technologies like OpenSSL, OpenVPN or Tor establish an encrypted tunnel that enables users to hide content and addresses of requested websites from external observers This protection is endangered by local traffic analysis attacks that allow an external, passive attacker between the PET system and the user to uncover the identity of the requested sites. However, existing proposals for such attacks are not practicable yet.

We present a novel method that applies common text mining techniques to the normalised frequency distribution of observable IP packet sizes. Our classifier correctly identifies up to 97% of requests on a sample of 775 sites and over 300,000 real-world traffic dumps recorded over a two-month period. It outperforms previously known methods like Jaccard's classifier and Naïve Bayes that neglect packet frequencies altogether or rely on absolute frequency values, respectively. Our method is system-agnostic: it can be used against any PET without alteration. Closed-world results indicate that many popular single-hop and even multi-hop systems like Tor and JonDonym are vulnerable against this general fingerprinting attack. Furthermore, we discuss important real-world issues, namely false alarms and the influence of the browser cache on accuracy."

Also related (no account required to download the paper):

Compromising Tor Anonymity Exploiting P2P Information Leakage
http://fr.arxiv.org/abs/1004.1461

Pere Manils, Chaabane Abdelberri, Stevens Le Blond, Mohamed Ali Kaafar, Claude Castelluccia, Arnaud Legout, Walid Dabbous (All - INRIA Sophia Antipolis / INRIA Rhône-Alpes)

"Privacy of users in P2P networks goes far beyond their current usage and is a fundamental requirement to the adoption of P2P protocols for legal usage. In a climate of cold war between these users and anti-piracy groups, more and more users are moving to anonymizing networks in an attempt to hide their identity. However, when not designed to protect users information, a P2P protocol would leak information that may compromise the identity of its users. In this paper, we first present three attacks targeting BitTorrent users on top of Tor that reveal their real IP addresses. In a second step, we analyze the Tor usage by BitTorrent users and compare it to its usage outside of Tor. Finally, we depict the risks induced by this de-anonymization and show that users' privacy violation goes beyond BitTorrent traffic and contaminates other protocols such as HTTP."