I've never personally used ruby on rails and never intend on it. I've seen fads like it before. Your question was that of platform for web apps and when to jump ship. I believe web applications should be platform independent ( so jump ship now ). The best web applications (custom or stock) on the net with the lowest cost for maintenance are currently PHP applications. PHP+Apache+MySQL is a favorite combo of web developers and it's widely used and supported. The software is free and the community supporting those apps is huge. You can install those three pieces of software on any platform so no need for a pre nup.
