1. You should have stated that you have a conflict of interest (37 Signals Partner) like I did mine (author of Ghostery).
2. The fact that Media6 Degrees, a behavorial targeter is on their site is binary. Look at the source, it's there, pretty simple. That is a fact and not a rumor or a guess.
3. 37 Signals has the best possible platform to state their case, their blog.
4. This is the reason I created Ghostery, transparency and user education. Every tracker it identifies has a page explaining what it purports it does, who owns it and contact info for that company. After reading all that, you the end-user, can selectively block trackers.
5. The belief that an average user should track down what trackers are on every site they visit and then contact each one of those sites for their side of the story before saying or doing anything on their end is flawed IMO. That should fall at least equally on the publisher to disclose.