Here's some info from the most recent IB bulletin:
..."
New Order Types
Traders may now use Custom Stop Orders to specify how stop orders are triggered. Triggers may be specified for a single last price, two last prices, or two bid/ask prices. To change a trigger method, right click on an order management line and select "Trigger Method". IB will continue to default to the current stop order trigger method if a change is not specified.
Native exchange held stop limit orders are now available for Globex. Simulated stop orders will no longer be available.
Auto trailing stop orders, which allow you to enter a limit order, with an automatic trailing stop order attached, are now available with TWS. In addition, standard trailing stop orders are now available within the IB API...."