The translate API is now at version 2 and Google anounced that will start charging for that service. Version 1 was officially deprecated on 26th of May and will be shut off completely on 1st of December. All the projects already created (before 24th of August) and use verion 2 of the API are limited and the limit will be reduced to zero on 1st of December. Also, there is a limit on the number of request the application can do per day. New projects with the Google Translate API v2 should pay for the service and there is also a usage limit of 50 million characters per month. The current price is $20.00 per 1 million of characters but you should visit Google Translate API site for more information and current prices.
Google started charging for translate API