Hi Jayant -
Unfortunately DIAC has put family sponsored skilled visas at the "bottom of the pile" in terms of processing priority, for some unknown reason. It is appalling that they have taken a group of applicants and have consciously decided not to give them anything that could remotely be called timely service. So as to how long it will take? No idea, it's up to DIAC now that they have given themselves the right to select certain groups of applicants over others. As you can see here:
Allocation Dates for General Skilled Migration Applications
They are now working on applications lodged over 4 years ago in March 2009. I would say you probably have a long wait ahead of you for this visa.
But wait, it gets better! If you're family sponsored, your sponsoring relative must live in a "Designated Area" at the time of decision (not application), so if your relative moves to a non-eligible area during the long processing time, your visa application is likely doomed. If your relative still lives in a designate area, you're OK though - he/she does not need to live in the same designated area that they did before, but it must be in a designated area at the time of decision.
Here's the current list of designated areas:
Designated Areas of Australia - Professionals and other Skilled Migrants - Workers - Visas & Immigration
Hope this helps -
Best,
Mark Northam