Bitcoin support is currently limited to adding fixed dollar amounts to accounts; there's no direct purchase option. Up to $100 can be added at a time, and presently the option is only available to US accounts. The Bitcoin support comes via BitPay. Other early commercial Bitcoin supporters, including PayPal and Newegg, also use BitPay.
We understand that the company has no plans at this time to add support for Linden Dollars, InterStellar Kredits or Project Entropia Dollars.