To be honest, it's more than a year out of date, and not the best resource. We've talked internally about a replacement, but need to spec it out and find a contractor (and we have so many other improvements/upgrades/features to PRO we're in the process of making).
That said, I'll ask the team to look into it further. I do think a great directory list would be a valuable part of PRO content.
postscript update: We have a project in process to replace this with something very cool, updatable and more scalable, too. I believe launch ETA is Q3 of 2011. Justin Briggs from Distilled and Cyrus Shepard from Moz are working on this together.
