Michael J. discusses the obligation of the consultant to pick proven technology for custom jobs, but comes to the conclusion that the question is out of sync. It should focus on potential, not risk. When it does, you start questioning terms like proven:

But what does “proven” really mean? It is important to consider the case where something new takes off fast. At lunch we were specifically discussing Ruby on Rails. Two of us thought it looked pretty good, and one person was thinking about a small test project to check it out. Ruby on Rails has the opportunity to take off quickly because Basecamp was built on it, and everyone who’s used it knows that Basecamp is an awesome product. When they find out it was developed in two months by one guy they cannot believe it. Why only two months? Ruby on Rails, supposedly. Sometimes “new” becomes “mainstream” very quickly. It appears that this could happen to Ruby on Rails this year. That brings with it a host of potential problems, but obsolescence isn’t one of them.