Local. Local. Local. That's the point lots of people miss in conversations about businesses such as Pandora and Foursquare. These companies, like Twitter and Facebook, will compete for and secure national ad buys. However, local is a critically important battleground. The only way you win local is to put hustling feet on the street. It's an expensive proposition. Pandora -- and terrestrial radio before it -- serves as a model on how to do it well, but the company has been building its infrastructure for years. More important than its first-mover advantage, though, Pandora brings value to prospective clients. Personalized radio powered by a proprietary and wholly unique system. It not only targets users, it superserves them; it can sell the same proposition, inversely, to advertisers. Foursquare simply is not there yet. Not even close. In an increasingly crowded mobile new/social media marketplace with aggressive and exciting new entrants, you no longer have the luxury of time. More startups will succeed over the next one to five years than ever before, but many more will fail. As it stands, Foursquare could end up wallowing in the latter group. Follow @rocco_thestreet --Written by Rocco Pendola in Santa Monica, Calif.