Although we've heard this before from companies and things can change rapidly, at least according to one community manager at Grooveshark, that company won't be making a dedicated Windows Phone app despite already having ones for Android, iPhone (jailbroken), Blackberry and even webOS. In an email back and forth between a customer and Jessica, a community manager at the company the info was revealed:
Anonymous : "I was wondering if, in the near future, you would develop an application for users of Windows Phone 7. You are on all other platforms except ours."
Grooveshark response (Jessica - Community Manager) : "Hey E *****, Thanks for Taking the time to write us. Unfortunately, Grooveshark is not planning on Developing for Windows Phone 7. We're very sorry for the inconvenience and confusion. Please let us know if You have Any further Top questions. "
Of course, reps can be wrong for companies (although Grooveshark is very small, so less likely) and they could change their minds at any point. Still, we're none to happy with that response. Even though we have a working HTML5 version of their site now, having a dedicated app would certainly be more preferential. Hopefully they'll change their minds in the future.