The thing is that Grooveshark does not provide a public API, especially not a public API which allow you to write to their service. I was fortunate enough to get in touch with James Hartig who runs http://gsuser.com/ which is the closest thing to a public Grooveshark API though it doesn’t support writing to Grooveshark.
Through James helping hand i managed to get in touch with a Senior Developer at Grooveshark who gave me access to their internal API (Web 2.0 companies ftw, would this happen with Microsoft as an example?) and the project was on its way!
So, enough ranting – the service is available at http://groovylists.com/ – no bells and no whistles, but it currently imports 100 tracks from any iTunes based playlist. I’ll probably find some time this week to add m3u support as well, which pretty much make the project complete.
If you got any suggest and/or questions, either post them as a comment here or on the Grooveshark forums.