Welcome to another iPhone launch day. Apple's (Nasdaq: AAPL) much-heralded iPhone 4 hits stores today, and not just Apple's retail stores. Wal-Mart (NYSE: WMT), AT&T (NYSE: T), Best Buy (NYSE: BBY), and Radio Shack (NYSE: RSH) all had plans to sell the device to walk-in customers.

Whoops.

According to reporting by CNNMoney.com, none of these retailers had iPhone 4 models on hand. "Limited supplies" were so limited as to be nonexistent.

Investors should give this news a golf clap. Sellouts indicate higher revenue and, thereby, profits. It also puts pressure on Google's (Nasdaq: GOOG) Android partners to match features these rabid consumers find appealing.

But sellouts are also a problem. The New Apple is as much about volume selling as premium pricing. Having retail diversity should increase sales and allow the Mac maker to free up resources in its own retail operations, which are geared toward premium Mac sales and service.

In launching iPhone 4 through so many retailers, Apple could exceed its huge iPad performance: 3 million units sold in 80 days. That's the good news. The bad? Maintaining a robust sales channel involving many partners is never easy, and with today's instant sellouts, Apple appears to be off to a dubious start.

Apple and Best Buy are Motley Fool Stock Advisor selections. Best Buy and Wal-Mart are Motley Fool Inside Value picks. Google is a Motley Fool Rule Breakers recommendation. Motley Fool Options has recommended a bull call spread position for Best Buy. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Tim Beyers is a member of the Rule Breakers stock-picking team. He had stock and options positions in Apple and a stock position in Google at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. The Motley Fool owns shares of Best Buy and is also on Twitter as @TheMotleyFool. The Fool's disclosure policy is channeling good karma to your portfolio.