The RS Spread has flattened out after the laggard rally of much of 2009. I suspect that this base-building period may be followed by an even more favorable environment for relative strength investing.
The chart below is the spread between the relative strength leaders and relative strength laggards (universe of mid and large cap stocks). When the chart is rising, relative strength leaders are performing better than relative strength laggards. As of 5/24/2010: