More info....
An important note:---
This is own my experience. Please verify the facts through your own and reliable sources.
My employer decided to disown me in Nov'02 because my project was coming to an end. He planned not to pay the bench salary and to withdraw my 140 and use my LC for another employee. He has done this before to another guy.
I contacted local congressmen and asked them to enquire on 140 because my 140 was pending for more than 180 days that time. They contacted INS and got a reply that it will take a while to process June cases because they were processing Feb cases at that time. They cannot do anything on the case. I told the rep's office that i will be laid off soon and 140 might be revoked by emp. So, they contacted Ins again and they were told that since the 140 and 485 were filed concurrently (though 3 months apart), i can change jobs immediately with similar title,type.. and send them a letter from the new employer... At that time, my 485 was pending for 3 months...
I haven't used AC-21 yet, I got another project in Nov itself and i am continuing with the same employer. 140 is still pending. If i get a job in a good company, i'll leave this guy and join them before 180 days of 485... Again, many companies are not ready to hire before 180 days....
Again i am telling you friends -- whatever i have wrote is my TRUE experience. I am very skeptical about their suggestion - some officer might have given misleading or wrong info or it might be the right information. That why I am telling it is strange.
Consult a good attorney and take the risk.....