A Flash widget on Myspace will do the job pretty well. It lacks the integrated Myspace functionality that their widget has, like the “add” button to add a song to your profile, but that’s not a big loss.
So, yeah, this is absolutely a win. On Myspace a musician just needs to set up a widget that auto-imports their music from a standard URL they host. That’s what I did for my own profile. And it’s incredibly convenient — I just add a blog entry tagged “audio” to the soupgreens blog and any MP3 link in the entry will show up in the player on my Myspace profile.
The downside is theoretical on Myspace. If they ever get their act together with vertical features like rating, it’ll become an issue. I figure they will do a big push here for the provisioning company they just created.