Sometimes it hurts to be the only game in town.

Just ask RadioShack (NYSE: RSH). The strip-mall electronics retailer sells the new Apple (Nasdaq: AAPL) iPhone 4S. However, it only carries the AT&T (NYSE: T) version, not like bigger gadget retailer Best Buy (NYSE: BBY), which also stocks Sprint Nextel (NYSE: S) and Verizon (NYSE: VZ) models.

Still, it's a start. This phone is set to enter the Guinness Book of Records as the fastest-selling electronic trinket of all time, displacing Apple's own iPad 2 from the top spot. Four million units shifted hands over the first weekend, which is twice the sell-through of the now-antediluvian iPhone 4. Any retailer worth its salt would kill for a piece of this action.

Best Buy locations are generally sold out. I'm pretty sure that all three of the networks are having a hard time keeping iPhone 4S units in stock. Go to Apple's own online store and you'll have to wait 1-2 weeks for delivery -- regardless of carrier.

Sadly, it doesn't look like consumers are connecting the RadioShack brand with the iPhone. RadioShack was sitting on a mountain of iPhones over the weekend, according to a company spokesman emailing Boy Genius Report. "iPhone 4s enthusiasts who are still looking to get their device late this afternoon or over the weekend will find them at their nearby RadioShack," spake the Shack. The 4S was "available in 3,000 stores nationwide" and the ship-to-store option is still widely available.

So we have the hottest electronics item in recorded history, available in large quantities while other retailers run dry -- and RadioShack has to beg for your attention.

Ouch.

RadioShack clearly doesn't cast a large shadow in the retail world today, try as it might. The Fool has real-world money in the company in two ways, via the Motley Fool Hidden Gems newsletter service and a Rising Stars buy. But even those seemingly bullish moves rest almost purely on rock-bottom share prices. As Anand Chokkavelu said when he bought some Shack back in February, "[H]onestly, I'm not really that stoked about the prospects of Radio Shack or Best Buy in the long term." Low-cost specialists Wal-Mart and Amazon.com (Nasdaq: AMZN) steal RadioShack's business on one end; the wireless networks themselves compete at the other end. And RadioShack gets lost in the crossfire.

RadioShack has been on death watch for years. Unlike Anand and my Hidden Gems colleagues, I don't think the stock is undervalued at all. This Apple debacle is simply one more data point to prove the Shack's growing irrelevance.

Will RadioShack bounce back, or is it a dinosaur on life support? Either way, our watchlist service will help you follow this story to its cheery or bitter conclusion. Just click here to add RadioShack to your own watchlist, and you're good to go.