It is a good sign when something you design solves problems not originally envisaged. This indicates depth and robustness.
Another good sign is when a third party of high standing makes a recommendation.
Both these signs are apparent in the increasing adoption of the Erlang language and libraries for distributed computing problems. Originally designed for telecommunications software, Erlang is now being used by Amazon, Facebook, and others as part of their infrastructure.
Also, Steve Vinoski, an authority on CORBA, an older technology for distributed computing, has been singing the praises of Erlang for largely "getting it right". In response Joe Armstrong (inventor of Erlang) has thanked Steve for going down the wrong path and living to tell the tale. Here's Joe on Steve, and Steve on Joe.
I hope that everyone working in distributed computing can take note of the lessons that Steve (and Joe) learned the hard way, without necessarily repeating all the hard yards.
Remember: It is always a good time to learn from other people's mistakes (and your own).