Place of filing IT return

Hi,

During the FY 2008-09, I worked till Aug 08 for a company in Chennai.  Then I shifted to Mumbai and worked from Aug 08 to Mar 09 in another company in Mumbai.  For the past 4 years, I have been filing my returns in Chennai.

For AY 2009-10, where should I file my return?  Can I file it in chennai, as that is my hometown?  Is there any clause that we should file the return only in our place of work?  If so, this year, I have worked in two locations.  Please clarify.
Regards,

Subhashini