Goldman Sachs signed off on Madoff?

Supposedly. When Tremont advisers was acquired by Oppenheimer, Goldman Sachs and Weil Gotschal, spent three days at Madoff's office, and signed off on the books.

Oppenheimer, represented by Goldman and Weil Gotschal, spent three days at Made-off's office running through the books before, it would seem, signing off.
http://www.dealbreaker.com/

"We are pleased to be joining forces with a leader in the alternative investment business," said John V. Murphy, Chairman and CEO of OppenheimerFunds. "We believe Tremont's multi-manager, funds-of-funds approach to hedge fund investing will appeal to many of our high-net-worth shareholders. Tremont's unique product offerings in combination with our distribution network will open up the world of alternative investing to a new segment of investors."
http://www.secinfo.com/dsvr4.4FCEa.c.htm

So Oppenheimer, has Weil Gotschal and Goldman Sachs in it's corner. Goldman says that a decade ago, they thought Madoff was a scam:

More than a decade ago bankers from Goldman Sachs' asset management division were despatched to Bernard Madoff Investment Securities to discover how the legendary fund manager maintained such consistently good returns.

The American banking giant prided itself on managing funds in-house but if it could get a better deal for its clients at Madoff, Goldman would gracefully admit it and allocate some funds.

One former Goldman partner said: "I remember the guys came back baffled. Madoff refused to let them do any due diligence on the funds and when they asked about the firm's investment strategy they couldn't understand it. Goldman not only black-listed Madoff in the asset management division but banned the brokering side from trading with the firm too.
http://www.telegraph.co.uk/finance/financetopics/bernard-madoff/3868896/Bernard-Madoff-fraud-Increased-scrutiny-in-hedge-fund-industry.html

But in 2001 Goldman Sachs helped facilitate this transaction?

I guess it's only a scam, of course, if you aren't getting any fees!