The program's cost has ballooned from $68 million to more than $700 million.Earlier posts:
Big-Time fraud in NYC time-and-attendance initiative (12/17/2010)
NYC payroll chief resigns after fraud probe (12/24/2010)
Biometric ID management technologies have the ability to help institutions to combat fraud but the implementations aren't inherently immune from corruption.
Nevertheless, even after the extreme cost overruns that increased the projected cost by a factor of ten, I wouldn't be surprised to see NYC recognize a positive ROI.
From Wikipedeia:
[In 2006] The New York City government's budget is the largest municipal budget in the United States. The city government spends about $50 billion a year, employs 250,000 people, spends about $15 billion to educate more than 1.1 million children, levies $27 billion in taxes, and receives $14 billion from federal and state governments.
$700M / 250,000 employees = $2,800 per employee
Depending upon the scope of inaccuracies in the NYC bureaucracy and the comprehensiveness of the system implemented, recognizing a ROI for the system might not take long at all.