It's a relatively new protocol. There may be laundering methods that nobody's thought of yet.
In China, Korea, Singapore, and Japan, virtual goods are considered property to varying degrees.
EDIT: reply to discountgenius since there was no reply link. One of the functions of government is to create laws protecting property. There aren't any laws in the U.S. that treat virtual goods such as bitcoin as property. In the U.S., at least, courts have proven extremely reluctant to extend property protections to virtual goods, i.e., MMO items, because the state of the law and underlying technology is still too much in flux. At best, virtual goods are treated as licenses. However, licenses are not property that can be stolen (and this has been litigated in non-virtual contexts).
In Japan and Korea a few years ago, some courts ruled that in-game purchases were considered property for specific purposes. I do not know if their respective courts followed those cases.