Best Buy, Inc. (NYSE: BBY) has gone shopping across the pond, and will be spending about $2.1 billion in cash to purchase 50% of the UK's Carphone Warehouse mobile telephone retailer. Best Buy is signaling to the retailer world that it thinks mobile is the place to be, after it committed to expanding mobile market share here in the U.S. just recently in a large way.

This multi-billion commitment to Carphone Warehouse will allow the European retailer to pay down debt and gets Best Buy a foothold in the European retail business in a pretty large and immediate way. Along with Wal-Mart Stores, Inc. (NYSE: WMT), U.S. retailers are seeking out ways to expand their footprints globally. Carphone Warehouse isn't just a small step in that direction, as it's one of Europe's largest mobile phone retailers.

Best Buy's revenues continue to soar on an annual basis, and this partnership should add to that amount significantly. While U.S. competitor Circuit City Stores, Inc. (NYSE: CC) has had nothing but troubles recently and is just hanging out in la-la land while delivering substandard results every quarter, Best Buy is going for the jugular -- still growing sales and taking market share in the U.S. and now in Europe. Can it be stopped? For now, there's no equal -- so, no.

In 2007, over 75 millions Americans purchased a mobile phone from a carrier-owned store, while roughly 5.5 million bought their handsets from a consumer electronics or other retail chain. That's quite an imbalance. But as networks open up and many handsets are sold in an "unlocked" state, does it make sense for carriers like AT&T, Inc. (NYSE: T) and Sprint Nextel Corp. (NYSE: S) to continue to operate their own retail stores?

After all, if the exclusivity of certain handsets is no longer the domain of a certain wireless carrier, why operate an expensive chain of national retail stores that compete with the fast-and-furious retailers like Best Buy, Inc. (NYSE: BBY) and Radio Shack Corp. (NYSE: RSH)? Although AT&T and Verizon Wireless won most of the licenses at a recently-completed FCC auction, one possibility that emerged from the auctions itself was the promise of being able to use non-carrier cellphones on any network which is technically compatible. For example, one could buy a Sprint Nextel phone and use it on Verizon's network.

Does this kind of move erase any incentive for carriers to continue operating expensive retail stores across the U.S.? That is the question retailers like Best Buy would like answered, as the largest consumer electronics chain in the U.S. would like to up its mobile phone sales market share from 2% now into the double digits within five years. Financially, it may make more sense for the large wireless carriers to eventually exit the retail business and let the mega retailer -- which has better overall selling efficiency anyway -- handle phone sales. It's already ramping up Best Buy Mobile, so the strategy may be underway anyway.

After hearing words of sorrow but optimism for the future from Best Buy (NYSE: BBY) executives this morning, I was wondering what the company has up its sleeve to shore up profits and keep growth happening. Sure, the services area of Best Buy's operations, growing relationships with customers and ensuring product mix stays consistent for the best margins possible are all good ideas. But one idea may be the jackpot of them all: cellphones.

Best Buy Mobile is more of an experiment than anything, but the largest consumer electronics retailer in the country wants to make sure its face is planted inside each and every future mobile phone user there is. To that end, it's setting up standalone mobile product sales centers to further its brand, earn more mobile phone commissions and really entrench itself as the mobile product provider of choice even as mobile phone subscriptions are showing signs of slowing growth. More and more advanced phones (and mobile emailers like Treos and BlackBerries) will become popular and the phone of old will become the electronic Swiss Army knife soon. Heck, that's already happening.

Best Buy's biggest foe here is Radio Shack (NYSE: RSH), which counts on mobile phone sales and plan sales to drive a healthy chunk of its revenue right now. Circuit City (NYSE: CC) dropped out of the game a few years ago, so for all the phones and plans that are not sold from mobile carriers like AT&T and Verizon, Best Buy and Radio Shack will be the big dogs. I'm of the mind that this is a fabulous strategy for Best Buy at relatively little cost compared to the potential upside.

Best Buy (NYSE: BBY), the largest consumer electronics retailer in the U.S., will be launching 150 to 200 Best Buy Mobile wireless stores in its New York, Boston and Texas markets. The phase-in of these Mobile stores will occur over the next 18 months, according to the retailer.

Best Buy just keeps on singing a happy tune with its performance. Its retail stores are way ahead of competitors Circuit City Stores (NYSE: CC)and CompUSA in terms of profitability, its Best Buy for Business division is healthy, and it acquired Speakeasy to enter the computer services arena even further. The company just can't seem to do wrong these days.

Best Buy's latest effort in the wireless landscape will include freestanding locations branded as "Best Buy Mobile" and kiosks within Best Buy stores themselves. I'm left wondering how the in-store units will be different than the wireless departments already inside Best Buy stores, however.

The company states that the newer Mobile stores will feature an expanded assortment of handsets, accessories and services. Wireless operators that will be offered include Cingular, Sprint Nextel (NYSE: S) and Verizon Communications (NYSE: VZ). Mobile virtual network operators (MVNOs) and prepaid services including Amp'd Mobile, Boost Mobile, Cingular Go Phone, Verizon InPulse and Virgin Mobile will also be offered.