There are now more than 100 million web-tethered devices running Apple's (Nasdaq: AAPL) iOS, and Sirius XM Radio (Nasdaq: SIRI) wants to find a home in as many of the iPhones, iPads, and iPod touch media players as possible.

The satellite radio giant announced a significant update to its existing App Store streaming application yesterday.

The biggest upgrades will be found on its music channels. It will do what many Internet radio stations have been doing for years in offering up album cover art and artist bios for the tracks playing. An iTunes shopping cart is also integrated into the app, allowing users to buy the songs that they are hearing through Apple's iconic digital music store.

A nifty "lookaround" feature will also let subscribers see what's playing on other stations without having to go around the dial to find something they might like. There will be extra eye candy on the iPad-optimized app to make the most of the tablet's larger screen.

There are also some technical updates going in to enhance audio quality and improve network connectivity. We'll see if they provide a marked difference to the streaming experience.

If successful, Sirius XM will likely roll these bells and whistles into their apps for smartphones running on Google's (Nasdaq: GOOG) Android and Research In Motion's (Nasdaq: RIMM) BlackBerry. Sirius XM introduced premium streaming on Apple gadgetry two years ago, months before rolling the application to BlackBerry and Android smartphones.

Streaming has apparently been a hard sell for Sirius XM. Sirius XM was quick to tout the brisk volume of download activity when it made its App Store debut in 2009, but the company has been tight-lipped as to how many of the millions that have downloaded the application are actually still using it as paying customers.

Pricing has been an issue. The offering is a reasonably priced add-on for existing receiver-based subscribers, but it's a bit steep as a stand-alone offering. Competition is another issue. It's easier to go up against terrestrial radio in the auto dashboard than it is to compete against free sites including Pandora, CBS' (NYSE: CBS) last.fm, and countless other ad-supported streaming websites on smartphones.

Wireless carriers have also moved away from selling unlimited data plans, making premium streaming a potentially costlier luxury.

Sirius XM is hoping that will change that year. Howard Stern's show finally became available for app streaming this year. This week's interactive application update should also improve the value proposition.

Streaming may never grow into a monumental needle mover for Sirius XM, but it's a market that's obviously growing a lot faster than the auto market. Sirius XM can't -- and won't -- ignore that.

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