In order to get the Panasonic Lumix DMC-LX1 (or Leica DIGILUX-2) to work in Aperture you first have to convert it to DNG using Adobe DNG Converter. Then you follow these directions which a commenter provides the trick.

1. Open “/System/Library/Frameworks/ApplicationServices.framework/
   Versions/A/Frameworks/ImageIO.framework/Versions/
   A/Resources/Raw.plist” as an administrator.
2. Search “DMC-LC1” and copy the chunk of XML in there
3. Replace the “DMC-LX1” with “DMC-LC1” and the “C-LUX 1” with “DIGILUX 2”
4. Save file

Now you can import the DNGs into Aperture or iPhoto and the previews will now work.

Anytime you update the system software or QuickTime, this file might be overwritten so you have to go through the same process again.