From: Zune Thoughts:

Adam Krebs on Zune Thought recently posted his thoughts on a tagging work-around to help those with tagging woes.  Very effective especially if your wondering why your music doesn't have album art or show up in your "recently listened to" music in the Social.

His excerpt which references Shawn Oster's Blog is just another reminder that we are waiting for a Zune Software update that would put us back in control of our music libraries.  At the present time the software doesn't have the capabilities that we need to properly manage our music. "Make it your own" Without being able to provide any positive feedback for a solution, I revert to talking about temporary alternatives.

Shawn Oster points out how easy it is to hook the backend of the Zune marketplace into MP3Tag to get properly tagged and recognized files. He also points out that this could be helpful in getting Social to recognize the songs you play (though I'm not convinced of his argument that Social takes the album metadata from your computer--I'm pretty sure that comes from their servers).

He brings up another cool tidbit: "zune.net just made their 800x800 album art available via the back-end service I'm using so now you can grab full 800x800 album art even on tracks you didn't purchase directly from the Marketplace. Just download Marketplace.zip and extract the single Marketplace.src into your %appdata%Mp3tagdatasources folder and you'll be rocking! I'd also suggest you download the very latest beta of Mp3tag because the tag sources (what Marketplace plugs into) dialog is much easier to figure out for first timers, plus I always include the artist in the track listing and version 2.39n supports splitting this into the correct tags."

Source: Zune Thoughts