And neither are as safe as Rust is/will be with multithreading. Doing really pervasive concurrency is possible, but not particularly easy with those languages.
Basically, the borrow checker double checks your work. As you get better at not screwing up, it'll become less and less of an issue. When you're just starting out, it can seem way harder, because you're not used to having those restrictions checked.
http://www.indeed.com/jobtrends?q=scala%2C+rust%2C+Clojure%2...
As for the web stack: Play, Scalatra, Spray, etc... It can also use the fairly mature Java libs as well: Jersey, Jetty, etc...
On the other hand, I don't know of any popular projects that are written in Rust, other than what Mozilla is doing with Servo.
I can name companies as well: Twitter, Airbnb, LinkedIn, Gilt, Foursquare, The Guardian, etc...
Github still probably runs mostly on Ruby as well, and for performance, you could use JRuby.
Some of the top contenders:
* cpollcppsp (C++)
* go (Google)
* hhvm (PHP JIT by Facebook)
* openresty (LuaJIT on Nginx)
* undertow (Java)
* gemini (Java)
According to http://www.techempower.com/benchmarks/, the 2nd position is held by a Java framework, losing only 13,5% to the C++ overall winner. Granted, you need a 3rd party library to have something similar like goroutines / fibers / actor concurrency / whatever, but its all there if you want it.