In the past I have written a post about a bug in Picasa (post is in Dutch). The bug was that Picasa changed the timestamp when exporting a RAW file (Canon CR2) to JPEG.
I have tested this issue a few times since my post. Today I checked again. Now it seems to be working!
After the conversion there is still some metadata missing or changed a little bit. But that is not a big issue at all. A correct time is much more important since it is used for sorting in galleries, etc.