Delivering Software, Electronically?

zpengo asks: "I'm trying to find the best way to implement a large-scale Electronic Software Delivery (ESD) service for my software company. I've been able to find very little information online (after weeks of research) so I must take it to America's best and brightest. Have you ever worked with ESD on a higher than plain-vanilla FTP level, and if so, what did you learn from it? When do you consider the product 'delivered'? Was it worth it? (I'm planning to put together a public domain whitepaper on the subject with the information I gather, to help fill in the gaps I found while researching online)."