As we mentioned earlier in this blog post, the default BitmapScalingMode has changed from Fant to Linear. If you compile your app for 4.0 and notice scaled bitmaps looking worse, this is why. If you want the old look, set the mode back to Fant.
Fant produces the best looking scaled bitmap but the scaling is done on the CPU at certain intervals. This CPU usage can make your scale animations stutter. On the other hand, Linear is done entirely by the GPU so everything is smooth but the quality suffers. Linear may also use more video memory than Fant but that depends on the scenario.