No cash? Festivalgoers can pay with their phones Keys, wallet and cell phone. Most people don't leave home without them. But what if you could ditch your wallet? PayPal, Google, and other tech companies are working to turn your smartphone into a mobile wallet, where you can pay with just a tap or swipe. CNET's Kara Tsuboi headed out to San Francisco's Outside Lands music festival to see if mobile wallets were really more convenient.