While the Bitcoin market is advancing toward legitimacy in the financial world, that also means closer legal scrutiny -- and the Mt. Gox exchange is tightening its policies to match. As of today, the institution requires verification for every non-Bitcoin deposit or withdrawal. The move keeps Mt. Gox in line with "strict anti-money laundering rules," and it reduces the chances that security breaches will spark chaos. Verification won't be necessary for pure Bitcoin transactions, the exchange says. Some traders see the new rule spoiling dreams of a truly borderless currency, but it may help reassure those still skittish about virtual cash.