One take-away message from the TheServerSide symposium for me was(*): multi-language development is considered to be an important change in the future. In particular, DSL are hip at the moment, but some people think that in the future there will be many languages that we develop in at the same time.
If I knew what the next big thing was I had better things to do than writing blog posts. But my guess is that it will be something around small connected devices. We might look back and say that the Blackberry and the iPhone were early signs. If that turns out to be true than this new language will have a portable runtime, be small in size and extensible. I also guess that it will be open source from the start.
(*) the others were: Spring is as fat as J2EE and SOAP is so dead that even its proponents stopped defending it.
Update: just saw that TSS has an April's Fool post along these lines