It means that when the delegates vote, 41 of Santorum’s delegates are not obligated to vote for him. Only 3 of Newt’s are non-binding. Pledged delegates (binding delegates) MUST vote for that candidate. In other words, if Santorum tanks all 41 delegates can change their votes.
Here is a good website with a lot of info regarding the primary selection process
http://www.thegreenpapers.com/P12/R-HS.phtml