The current CPF minimum sum of $99,600 will go up to $106,000 from 1st July this year. This is the amount of CPF monies that you have to set aside before you can withdraw the rest. Upon reaching 55, the minimum sum will be moved to your retirement account, and you will start getting a monthly payout of about $960 from age 64 for the next 20 years.
The Medisave minimum sum will also go up from $28,500 to $29,500 while the cap on the Medisave contribution ceiling will go up from $33,500 to $34,500.
There is also a phasing out of the 50% withdrawal rule for those who are unable to meet the CPF minimum sum. From 1st January 2013, CPF members must meet the CPF and Medisave Minimum Sums first before they can withdraw their remaining Ordinary Account and Special Account balances at age 55.
The complete press release with details of the changes can be found on this page of the CPF website.
Going ahead, you can expect the minimum sum amounts to be revised upwards every year to factor in inflation.