Clamp down on virtual currencies. Liberty Reserves down who would be next?
With shut down and prosecution of Liberty Reserve; authorities in US have clearly declared war on virtual and crypto currencies like bitcoin, litecoin and PPcoin.
Here is a presentation on understanding crypto currencies like bitcoin
http://www.businessinsider.com/presentation-what-is-bitcoin-2013-3#in-theory-no-one-controls-it-and-you-can-also-take-it-anywhere-since-its-just-code-10
Most of the e-commerce carts like Opencart , Magento ,Prestashop have bitcoin payment plugins which will allow a merchant to accept bitcoin or litecoin as payment through payment gateway providers like bitpay.com.
However to accept or not to accept crypto curries as payments is a matter of judgment. As the things stand crypto currencies sit between gray-zone of legal and illegal.