There's buzz building over a Sirius XM Radio (NASDAQ:SIRI) event next week, at which the satellite-radio giant may introduce some new hardware.

One of the new items being rolled out, according to industry websites and Orbitcast, is the SkyDock plug-in device, which turns any iPod touch or iPhone into a satellite-radio receiver.

The SkyDock itself isn't rumor-mill chatter. Sirius XM has recently filed compliance reports with the FCC detailing the device. It may or may not be introduced next week, but it's definitely in the works.

Will that even matter? The Sirius XM streaming application that hit Apple's (NASDAQ:AAPL) App Store hasn't lived up to the initial hype.

"The number should not be a significant number," CEO Mel Karmazin responded during Sirius XM's second-quarter conference call this month, when asked about the subscriber impact of the Apple program.

Despite a healthy marketing push, there are two logical theories behind the Sirius iPhone app's self-admitted insignificance, early on:

  • iPhone and iPod touch owners have access to free ad-supported online radio, including Pandora, CBS's (NYSE:CBS), and Yahoo!'s (NASDAQ:YHOO) Y! Music. Sirius XM offers superior programming, but it's not the same kind of quality disparity that drivers experience when their only alternatives are typically stodgy terrestrial radio or old CDs.
  • Unlike the conventional satellite-radio service, the Apple streams lack some of satellite radio's more popular content, such as The Howard Stern Show and live NFL and Major League Baseball games.

If you subscribe to the first theory, the SkyDock is toast. The SkyDock and its chunky satellite antenna will only make the iPhone less portable.

SkyDock's chances are far better to those who blame the App Store disappointment on the lack of Stern and coverage of live sporting events. SkyDock serves as an actual satellite receiver, so subscribers will be tuning in to the same content as the drivers with Sirius or XM in their cars.

Of course, consumers have been able to buy portable satellite radios for years. Lugging around a dock with an antenna doesn't seem any more convenient than purchasing a sleek stand-alone receiver. Sirius XM will also probably price a SkyDock connection as a regular subscription, or a more expensive secondary receiver for existing subscribers, than the $3 monthly rate they would pay for simply streaming online through their App Store program.

We can only hope the SkyDock brings more to the table than that. If not, it will be the second time that Sirius XM bulls get all riled up about an Apple tie-in that bears minimal fruit.

Other ways to slice and dice satellite-radio fandom: