Found the comparison chart I based my comment on
https://wiki.fourkitchens.com/display/PF/Comparison+-+Pressflow+versus+Drupal
There are several notations that say unique to Drupal.org
Gregg
From: support-bounces@drupal.org [mailto:support-bounces@drupal.org] On Behalf Of Ms. Nancy Wichmann
Sent: Thursday, July 28, 2011 4:08 PM
To: support@drupal.org
Subject: Re: [support] What is the largest Drupal site as far as the number of rows within the node table and how is the performance?
I don't believe that they've done anything that any installation wouldn't have do to scale beyond a single server. It is documented somewhere (try a search on "load balancer"). Acquia has done something similar and there is documentation on that somewhere too.
Nancy
Injustice anywhere is a threat to justice everywhere. -- Dr. Martin L. King, Jr.