This is shaping up to be a defining week for streaming music.

Pandora (NYSE: P) beefed up its service with the launch of a revamped website yesterday. The new site offers quicker loading times, easier controls, beefed-up artist information, and more intuitive station creation.

More importantly -- for the cynics that point out the flaws in Pandora's usage caps under its free ad-supported version -- there are now no more listening caps. Well, if you do go over 320 hours it will kick in some "abuse prevention" protocols, but you probably do need an intervention if you're averaging more than 13 hours of music streaming a day.

This is really just the beginning, though.

Today, Facebook is introducing new features that make it easier to stream and share music within its widely popular social networking site.

Tomorrow just happens to be the day for Clear Channel (OTC: CCMO) to officially introduce the ballyhooed iHeartRadio app, spearheaded by a two-day superstar-studded music festival to promote the relaunch. The new application adds Pandora-like features to the original platform for streaming hundreds of Clear Channel terrestrial radio stations. In short, it's now both a DJ and a jukebox.

Missing from this week's glitz is Sirius XM Radio (Nasdaq: SIRI). Unlike the many free options, Sirius XM isn't free to stream. It will set premium radio fans back $13 a month, or just $3 a month if they're existing receiver-based subscribers.

Sirius streaming doesn't offer the same kind of musical breadth as its free rivals, though it's untouchable when it comes to talk and sports programming. Is that enough? Will it be enough after this busy week of upgrades elsewhere?

Is it time for Sirius XM to introduce Internet Listening Lite -- a free ad-supported app that offers limited streaming access? It would be a delicate balance, since it would have to offer enough to convince freeloaders to make the switch. By the same token, it would be a great tool to promote the premium content that listeners would need to pay to receive.

Sirius XM can't stand still. The free competition is getting better this week. Your move, Mel Karmazin.

Will Sirius respond on the streaming front? Follow along by adding Sirius XM Radio and Pandora Media to My Watchlist.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.  

Longtime Fool contributor Rick Munarriz calls them as he sees them. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.