[DanielRibeiro]

Just because you are not aware of what is being used, does not mean that it is not used. Scala startups: KaChing (follow http://twitter.com/eishay for more info, he talks a lot about the Lean startup practises on Kaching as well) and Etherpad (wave-like product, bought by google last year). Eishay also gave a great hint for startups looking for scalable technologies: http://twitter.com/eishay/statuses/20478841811

Flightcaster, which is funded by YCombinator, uses clojure and Ruby on heroku (more on their infoq profile: http://www.infoq.com/articles/flightcaster-clojure-rails).

Most startups are not actually vocal about what they use. Most of them actually are not heard, so they could be as vocal as they wanted and still noone would hear them.