Received this from them in September:
New site feature: More ways to trade small-cap stocks
It's now possible to short sell stocks under $5 on our Web site. Another change coming soon will deliver quotes for pink sheet securities on the site, providing you with access to more information when and where you need it.
When trading OTCBB and pink sheet securities, please understand that they can be very volatile and are frequent targets of fraud and manipulation. When trading them, it's important to understand that you may lose your entire investment.² In addition, the risk of loss on a short sale is potentially unlimited (since there is no limit to the price increase of a security). Because there's no guarantee that a brokerage firm can continue to maintain a short position for an unlimited time period, your position may be closed out by the firm without regard to your profit or loss. You may only short sell securities in a margin account. Margin trading increases risk of loss and includes the possibility of a forced sale if account equity drops below required levels. Margin is not available in all account types.³