Not too sure. I have not used Picasa. You can download the demo version and try it yourself. I find it easier to use that the CS1 shadow & highlight dialog and the results are very much better.
There are still things that it cannot do (it is release 1.0b) and if the shadows are too dark, you will need to play with the saturation controls within LM. Sometimes, if there is not enough information in the dark areas, retrieval is impossible. Howver, the shadow detail retrieval is far superior to PS CS.
I use it almost 40% of the photos I take to get it to the way I like it.