Over the last few days we’ve seen a lot of attention centered on the new iPhone application from Spotify, the so-called ‘iTunes Killer’ subscription service that lets you plays songs on demand from a library of millions of tracks. We still don’t know if that app is going to make it through Apple’s nebulous approval process, but it’s already got some possible competition: Grooveshark, a streaming music service that lets you stream nearly any song from its web interface, has its own iPhone app ready for release and it’s just about to submit it to Apple. Like Spotify, the application lets you search for any song you want and stream it from the cloud almost instantly.

Now Grooveshark just needs to face the daunting Apple approval process. So will it make it though unscathed? Almost certainly not.

Grooveshark is a great service — the web interface is slick, and you can usually find whatever song you’re looking for in a matter of seconds, free of charge. But it’s also not exactly on solid legal footing. The company is holding true to its comparison to a ‘YouTube for music’, allowing users to upload whatever they want and generally only policing when they receive takedown notices, which doesn’t prevent the bulk of copyrighted songs from making their way onto the site (in its early days YouTube thrived on copyrighted content using a similar strategy) . CEO Sam Tarantino says that Grooveshark is currently hammering out deals with the major record labels to remedy this issue, but EMI changed tactics midway through negotiations and decided to sue the company instead which isn’t helping their efforts.

Still, Tarantino sounds optimistic about the future of the company, even if he isn’t counting on the iPhone app getting approved just yet. The website gets 1.3 million visitors a month, 750,000 of which have registered. The company is finalizing how it will deploy a subscription model (likely in the $5-$15 a month range), which will give it an added boost of legitimacy, and revenue. Until then though, I wouldn’t expect this to pop up in the App Store any time soon.