I just added a new feature to jME called TimedLifeController.  It is a convenience class for short-lived real-time actions that have to occur in a game.  Say for example you want to fade something into your game.  Instead of some complicated mess trying to do a smooth fade-in inside your update loop directly, you can create an implementation of this class, define the life in seconds, and implement the updatePercentage(float) that receives the percent complete between 0.0f and 1.0f.  This way you can smoothly fade the object in over the time you want in seconds and then when it's completed, it de-activates itself.

Let me know if anyone else finds this useful.  I couldn't figure out a good way to do it in jME now without defining my own controller, so I figured a convenience class would be beneficial.

sounds very nice!

A usefull class to have to simplify main game loop, thanks!