The purpose of the AC-21 law, as we know it, is to allow 485 petitioners switch jobs after 180 days of filing of th 485 petition and realize their enhanced income potential commensurate with experience and skill.
When this law was created, the concept of concurrent filing of 140 and 485 did not exist. This law basically assumed that an employment based immigrant visa was available based on which the petitioner had filed the 485 to adjust status to that of a permanent resident. Thus, when this law was written it was implied that 140 had to be approved as 485 could not have been filed, otherwise.
Per my recollection, the 08/03 memo deals with the continuation of the validity of an underlying approved I-140, whose beneficiary has a 485 petition pending for greater than 180 days since the time of filing AND has switched employers. To me, therefore, it is obvious that 140 has to be approved and 485 has to be pending for longer than 180 days, to accrue the benefits of AC-21 portability.
Above all, I believe that the USCIS has not published regulations for AC21 even after 3.5 years of the creation of the law for the reason - leave its interpretation open to suit any condition that arises.
There have been great many of us who have been cleared under the current circumstances. These in most instances are people who have filed 485s after their 140 were approved. I do not think there are enough approvals of AC-21 cases (there are some, certainly - I can recall atleast one case from CSC) who had filed concurrently.. and had switched jobs > 180 days from ND while their 140 was still being processed ....
There sure is a lot of thinking on the lines of "better safe than sorry" ....
Thoughts?