A question on visitor visa extension

[Pisa]

Hi,

I applied for visitor visa extension for my parents in August 2007 and i got the receipt from USCIS within 2 weeks but the application is still in pending status. I guess this is okay as long as USCIS dont reject it. But my parents plan to leave the US in another two weeks.
Here is my question. I sent the originial I-94 to USCIS for the extension (though, it is mentioned in this website not to do this, one of my friends got rejected due to this reason of not sending original I-94). So in the airport,while going out, is it just enough if my parents just show their receipt they received from USCIS for the extension of visitor visa along with passport ?.
If not, please advise what i should do in this case.
Thanks,

[PraetorianXI]

They do not need to show anything in order to leave the country. They will be allowed to leave freely with or without the i-94. But tell them to keep their boarding passes as evidence of their departure, so they can show that next time they attempt to visit the US.