Microsoft has released a word document which explains all the AD schema changes for Exchange 2010 SP2 to install and work properly. Download the doc here. To my surprise, the same doc has all the AD schema changes for Exchange 2007 & 2003.

Exchange 2010 SP2 Schema Changes

Though the doc is only 1mb in size, it is packaged in an msi file, which needs to be installed.

--> Please see the rest on the blog : http://www.howexchangeworks.com/2011/11/exchange-2010-sp2-ad-schema-changes.html