I was giving consultations at an immigration clinic in Boston recently, and met a Brazilian whose employer had filed a labor certification for him under the 245i Legalization program of 2000-2001. The initial paperwork was filed prior to April 30, 2001, but the original employer was no longer in business, and the man wanted to know what options were available to him.
Some background: in many cases, beneficiaries of petitions filed under 245i can file in another category. For example, if the immigrant was the beneficiary of a 245i qualifying petition filed by his sister who was a U.S. Citizen, then he'd have a wait of around 12 years, judging by the most recent visa bulletin... or longer, if he were from Mexico or the Philippines. However, if there were another, quicker way available, then the immigrant could be "grandfathered" by virtue of the old petition (that is, file a new petition but keep the 245i benefit of being allowed to adjust status here in the United States.)
To do so, though, you need to be able to show USCIS that your petition was "approvable when filed." If not, you won't be able to benefit from the original petition, and you won't be able to take advantage of the grandfathering, either.
In the case I saw, the potential beneficiary didn't have the required job experience for the job at the time then application was filed, and so wouldn't have qualified for the green card in the first place. Again, if you are a potential beneficiary under 245i, make sure that you were qualified for the benefit as of the date of filing, before moving forward.