No. It is all taxable. What some of the schemes are exempt from is deduction of TDS like in MIS etc. Even Senior Citizen Scheme is subject to TDS. Currently PPF interest at Post office is exempt from tax. That will change once we migrate to EET regime in the new DTC.
Megha & Sunil are correct.Interest recieved from savings account in post office was exempt u/s 80L (deduction in respect of interest on certain securities,dividends,etc.).No deduction u/s 80L is available from assessment year 2006-07.