thanks for both of your help. The case is a bit complcated,

The reason they reject my H1B1 in Singapore is because of F1 status change to H1B1 in half a year in early 2007.

I am afraid US embassy Singapore will not give me the visa even though my H1B1 get approved in US.

My details are:
Aug'2006, i entered US on F1 visa
Feb'2007, I get H1B1 in US
Dec'2007, submit H1B1 for renewal (change employer/extension) before the old one expired. The petition is pending till today, 14-feb-2008.
Jan'2007, I went back to Singapore to apply for H1B1, it was rejected.
Feb'2007, I came back to US on F1.

up till today, my H1B1 petition is still pending. For this case, if my H1B1 petition is approved, is it still valid?