"As it stands, only 4 out of 482 measured top 500 sites are actively responding to the DNT header being sent." (Link)As a user, it's hard to tell if sites are honoring my Do Not Track request, and as a site developer, it might be a daunting task to hack up my back-end code. The W3C Tracking Protection working group at the W3C are working on helping out transparency and implementations, but in the meantime Jos has released his mod_cookietrack apache module to make it easier for site owners to track their users' clicks in a respectful way -- right now.
The Apache module, mod_cookietrack, does all sorts of stuff like mod_usertrack, but one thing it does better is honor DNT; if a server using this module sees "DNT: 1" in an HTTP request, it replaces the tracking cookie with one that says "DNT" -- something that's not unique to a visitor.
Apparently it was a lot of work to get DNT supported properly in mod_cookietrack, a native browser module that performs well and is safe on multiple threads, so thanks Jos for your hard work so that more organizations can support DNT on their web sites.