I have taken the radical view that this parable is all about advising the shrewd preacher to undo any harm he has done to his congregation by earlier sermons. ;-)
The following commentary on Luke 16:1-13 by Dave Mathewson from 1995 when he was pastor of Cardwell Community Church in Cardwell, MT might be useful as a resource for those needing a defense against the many modern interpretations that tend to show up in sermons these days.
"Recent alternatives to the traditional interpretation of the parable of the unjust steward are not compelling enough to overturn the traditional view.
Jesus has utilized a parable that portrays a steward cheating his master in order to secure his future but uses it to teach a positive, even if shocking, lesson on the prudent use of wealth. Christian disciples should display just as much prudence in their use of possessions, especially in view of the more important crisis that faces them—namely, the coming eschatological kingdom. Such prudence is an effective test of their ability to handle true, heavenly riches. It is also an effective test of their allegiance to God. Christians in this century, perhaps more than any other, need to hear this message anew."