What will IB bring to the table that SB doesn't? Its a die shrink, so expect similar results when Intel has done this in the past. What happened when the 45nm C2Ds came out? You got better thermal numbers, and an extra 500-600MHz on the OCs. I haven't heard of anything special on IB so I don't see why we can't expect the same thing again.
If your rig is fine and its not annoying you then don't worry about upgrading. Upgrade when it no longer does what you need it to.