Making Source Code Escrows Work
"Hundreds of companies pay thousands of dollars to set up source code escrows to protect their business critical software applications, so that if their licensor goes out of business, they can still get access to the source code and can continue to maintain the software. Unfortunately, though, in many cases these escrows are like having an insurance policy from a hopelessly insolvent insurer: In the one situation when you need it, it may provide no protection. But, as described in a recent article [from Farella Braun + Martel], with a few careful additions, source code escrows can be tweaked so that they do work in the real world."
From this IP Blawg post.