Could you please help me to find out my US tax return status for financial year 2009? Below is my and my wife USA visit history.

Myself:
18th May 2008 to 30th Sept 2009 (I was on L1 visa)

My wife:
18th May 2008 to 30th June 2009 (She was on L2 visa).

What will be my status for tax purpose? Resident or non resident alien? Please help?

Can we filed as "Married filing jointly"

You can file joint return as residents both for 2008 and 2009. You must both report worldwide income for 2009.