Does anyone know what Grooveshark.com is encoded in? I mean PHP, rails, flash ........?
The developer of Grooveshark is here. The Grooveshark backend is PHP 5.6, and the front end is a mixture of a ton of Javascript and a small flash pad that handles playback, https communication and several other one-time things that are easiest to do in flash than javascript.
This post may be useful: Technology behind the new Grooveshark
Looking through the source code, it looks like PHP (PHP / 5.2.14) and TON from Javascript.
Per WikiPedia:
Grooveshark is a rich Internet application that was first written in ActionScript using Adobe Flex that runs in Adobe Flash. In December 2010, Grooveshark introduced a website redesign that features an interface rewritten to use HTML5, which makes the interface faster.