The world's leading Bitcoin exchange, Mt. Gox, has announced a partnership with the Silicon Valley startup Coinlab. Under the agreement, Coinlab will handle Mt. Gox's American operations, which account for a large majority of the exchange's business. The transition will occur on March 22. CoinLab raised half a million dollars of venture capital last year. At the time, the firm was touting a scheme to exchange bitcoins for currency in games such as World of Warcraft and Second Life. Taking over Mt.