Google Accessible Search

Google Accessible Search supposedly ranks search results by Google's interpretation of "accessibility":
 
http://www.betanews.com/article/Google_Tests_Accessible_Search_Page/1153424136
 
It sounds great, but does anybody know just how they evaluate accessibility? I can't find a link that says "Check My Site," and the FAQ answers are more than a bit vague...
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Jacob Rose
jrose@lgb-inc.com
202-685-2461 (U.S. Army Center of Military History)
703-599-7028 (mobile)
Senior Programmer/Analyst
LGB & Associates, Inc.
 
US Department of Transportation 2005 "Prime Contractor of the Year"
US Department of the Treasury 2005 "Small Business Partner of the Year"