Investors are watching for an announcement that XM Satellite Radio (NASDAQ:XMSR) has surpassed the 6 million subscriber mark -- days after Sirius (NASDAQ:SIRI) announced that it has 3 million listeners on board. After next week's Consumer Electronics Show, however, "watching XM" may take on an entirely new meaning.

At the show, XM will unveil a decked-out Lexus concept car with its XM Advanced Series set of features. Some seem awfully futuristic, like using the company's personalized traffic updates to ferret out parking lot space availability, or voice command technology that provides the hands-free ability to find desired content. The application I'm most eager to check out, though, is XM's ability to stream video content thanks to its partnership with On2 (AMEX:ONT).

Streaming video over satellite radio is not a new concept. Nearly a year ago, Sirius announced that it will begin offering video content through a software partnership with Inside Value pick Microsoft (NASDAQ:MSFT) as early as next summer.

The quality of the video transmissions beyond cartoons, however, remains to be seen. Animated fare, though, would probably be just fine for satellite-radio streamers on the road who are seeking fresh content to entertain the restless kiddies in the back.

That's one thing that investors who may be bearish on satellite radio need to consider. A few decades ago, paying $20-$25 a month for cable television seemed preposterous when a pair of rabbit-ear antennas would pull in all the free major-network content. Then cable become an indispensable upgrade over the broadcast freebies. Then cable and satellite television providers began offering even more content and services, leading you to crack open that $95 DirecTV (NYSE:DTV) monthly bill.

No, XM or Sirius will never be commanding $95 monthly ransoms. However, when XM initiated a 30% price hike that went into effect back in April, nobody backed away. In fact, three months later, XM had to raise its guidance for its year-end subscriber count. As many of next week's features begin to roll out, XM will either be able to raise rates across the board or introduce premium offerings.

This should work out well for XM subscribers. After a great run through 2003 and 2004, the shares have stalled in 2005. That allowed Rule Breakers subscribers to get in at a reasonable price after it was recommended two months ago, given the sector's potential.

The only thing investors would want to see more than a successful video rollout -- for now -- may be CEO Hugh Panero announcing that XM has hit the 6 million subscriber milestone that he projected would happen by the end of the year. Panero has erred on the conservative side in the past. With Howard Stern joining Sirius a week from Monday, the last thing XM needs is to relinquish its leading role in signing up new subscribers.

We're watching, XM. Now just give us something to look for.

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Longtime Fool contributor Rick Munarriz thinks it's cool that Sirius broadcasts The Motley Fool Radio Show four times over the weekend. He does not own shares in any of the companies mentioned in this story, but he is a satellite radio subscriber.The Fool has a disclosure policy. He is also part of theRule Breakersnewsletter research team, seeking out tomorrow's ultimate growth stocks a day early.