It's never too late to crash the BlackBerry party -- as long as you're the DJ.

Amazon.com (Nasdaq: AMZN) is finally rolling out its MP3 store as an app for Research In Motion's (Nasdaq: RIMM) iconic smartphone.

BlackBerry owners who download the free app can check out 30-second samples of millions of available tracks, just as someone would on Amazon.com itself. They can also purchase songs and albums to download right onto their handsets.

Amazon and RIM make a good match. Think about the other companies behind the leading smartphone platforms. Apple has iTunes. Microsoft has Zune. It won't be long before Google makes a bigger splash in music. RIM is too busy trying to tell investors that it's still a growth stock to worry about launching a proprietary digital music platform. Why did it take this long for Amazon and RIM to make the process this seamless?

Amazon is unfashionably late, but it's going about this the right way. The leading online retailer is offering free songs and album deals daily. It's a win-win-win, since consumers get a free track, Amazon gets its foot in the door, and both the artist and Amazon will win if the freebie drums up sales for the complete album. This obviously isn't some breakthrough trick. Apple's mighty iTunes has been doing it for years.

Developers are starting to embrace the BlackBerry platform, and understandably so. The gadgets may be portrayed as email-centric handsets for corporate types, but these same owners have ear buds and long commutes. When you have a user base in the tens of millions, the opportunity is obvious.

It took awhile, but it's good to see Amazon and RIM jamming together.

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