I too have an LUD on my approved I-140. My I-140 was approved on 5/5/05 and it shows an LUD on 6/3/06. My PD became current in April'06. My name check has also been completed in Feb'06. When I made an inquiry, I was told that there are additional security checks being conducted and so my I-140, I-485 have been in the security area since March 30, 2006. Since there was an LUD on the I-140, I am assuming that the "additional" security checks have been completed.
PD 1/02
I-140 RD 7/03
I140 AD 5/05
I485 RD 5/04
I485 AD ??/??