GrooveShark is a web application intended to create a new business model for music, being legal and yet using all the things that make p2p networks a success (including getting music for free). As they say in their blog,
Grooveshark is a web-based application for sharing music within a community of music lovers. We distribute DRM-free MP3s across a mostly p2p network.Adding to that, it also has a lot of social features, that you're used to see in other services like Last.fm.
In the 26th of March they started their limited alpha release (click there to request an account), and yesterday I got an invite to be part of it. The thing with it is that GooveShark isn't 100% web, and it has a lot of stuff (including registering) that can only be done with their desktop application. At least for now that application has only a Windows and a Mac OS version, so I wasn't able to try it. I tried to run in on top of wine, but I couldn't (something to do with the instalation of the JRE). Well, that at least tells me that the application is written in Java, so I guess it will be easy to do a Linux version, and I surely hope they do it. I wrote them an email asking about it but had no reply until now. Well, I guess that I'll have to wait until they wake up ;-) As soon as I have a reply about it I'll write it here.
Until then... Mashable also got an invite, and they covered GooveShark in their blog. So, if you're interested, take a look at it here.