ClientLogin authentication support for the AdWords API and the DoubleClick Ad Exchange SOAP API 
will sunset along with v201309 on 
July 21st, 2014. You only have 
two months left to migrate - don’t wait until the last minute!
We have plenty of resources to 
help you migrate. It might take longer than expected to migrate to OAuth2, especially if you don't already use a single top-level MCC to manage your AdWords accounts or if you are a DoubleClick Ad Exchange customer.
Start your migration as soon as possible and reach out to us early on the 
AdWords API Forum or the 
DoubleClick Ad Exchange API Forum with any questions.
- Ray Tsang, AdWords API Team