It requires a specific chain of events to trigger the problem, however: if the nuts on one of the rear suspension arms weren't tightened enough after a wheel alignment, there's a chance the arm may have play in its adjustment, which might then lead to rust.
If sufficiently rusty, the arm could then wear at an accelerated rate and, eventually, separate from the mounting point. If that were to happen, the car could become difficult or impossible to control.
This is a voluntary recall by Toyota, and while it was announced today, no remedy has yet been devised. Once it is, owners of affected vehicles will be contacted via mail to setup a no-charge appointment at a Lexus dealer.
For more information, or to see if your car is covered by the recall, you can contact Lexus' recall center on the web or call their Customer Satisfaction line at 1-800-255-3987.