It also works more efficiently on the back end. Unlike conventional systems of this sort, including the Postini product, Vault doesn't make copies of the content it tracks and put it in separate repository. Instead, when end users "delete" emails and IM sessions, they are only removed from their interface view but not deleted from Google Apps servers.

He also said that Vault's price puts it within reach of small and medium size businesses that traditionally haven't been able to afford this type of system, whether cloud-based or on-premise.

For the time being, Google will continue offering both Vault and the Postini product.

Currently Apps Vault is only available to new Apps customers signing up for the service for the first time on or after Wednesday. Later, Apps Vault will be available to existing Apps customers, and Google will offer automated data migration for companies that use the Postini product and want to switch.