I recently were in the Swedish alps and did some filming while skiing. Sadly when I got home I noticed that all the movies have been overexposed and I now wonder if there is somehow I can fix this in PE 7?
You might be able to improve the footage, albeit slightly, by placing your footage on Video Track 1 and a copy of it on Video Track 2. Play with the Opacity of the Clips on VT2 and monitor any improvement. It will be slight, and with blownout highlights you will never fully recover much detail. However, along with Steve's tips, plus this method, you might get material, that you can live with. The Levels Effect can also help - a little.
Up to a point, underexposed footage is a bit easier to deal with and Highlight & Shadow, plus some video noise reduction can do more to save the footage, than with overexposure.
It will probably come down to using several Effects, and then living with the results. Do not expect miracles.