Hi Dinesh,
5 months sounds too long to send back the passport. From what I have researched, it should not take more than 8 weeks after they ask for the passport. Maybe it would be a good idea to call and find out what is happening.
Also, when did they start processing your wife's application? The reason I am asking you is because maybe they asked for your wife's passport before they started the processing her application?
My application (in New Dhelhi's Office) started on 23rd April 2008 and I have not heard any thing from them yet.
Thanks
Mridula