Due to the way in which Lightroom 2 and 3 handle RAW images, certain settings such as extra brightening and contrast are applied at import. These settings are a starting point for presets and are hard coded.  If you apply a preset optimized for RAW to a JPG image, it will be too bright, have too much contrast, sharpening and noise reduction.  Likewise, if you apply a preset optimized for JPG to a RAW image, the photo will lack contrast, sharpness, and be overly dark in most cases. Our Develop Module presets, Quick Clicks Collection and Mini Quick Clicks are available in versions optimized for both RAW and JPG.  Use the presets for your specific file type for the best results.
 

Upgrades in Lightroom 4 eliminated the need for different presets for RAW and JPG photos.