Hello everyone. I am pretty sure you have heard about the lens correction that detects your camera/lens and tries to adjust the issue (unless you have been living in some remote place than you may not have heard about it… 😉 ).
When you import the images into Lightroom, it tries to detect the camera/ lens combination and correct the lens distortions.
The Metadata for identifying lenses is becoming a standard but it is not yet. With the recent release of EXIF 2.3 it comes closer however there is no official standard of writing the lens metadata so sometimes Lightroom may not get it right and may not know what lens was used. Adobe is working on it all the time and they are bringing more lens profiles even though some “popular” lenses may not be there yet.
Even if your lens is not there yet, you can manually adjust controls or you can build your own profile using Lens Profile Creator. There are quite a few lens profiles already built in into Lightroom 3. A screenshot below shows the profiles for Canon:
I hope this helps.