Apple Pay comes to Costco, but Walmart remains a holdout

Corrections & Clarifications: A previous version of this article misidentified who gets a cut of the transactions if Walmart joined Apple Pay. The banks used through the Apple Pay app would receive a 0.15 percent cut.

Mobile revolution shakes up Silicon Valley

Smartphones, tablets and other gadgets aren't just changing the way we live and work. They are shaking up Silicon Valley's balance of power and splitting up businesses. Long-established companies such as Hewlett-Packard Co. ...