Itunes App Store Release Date Missing
The way I understand the question, I offer two answer paths:


If you are looking for an application version update date (sometimes also called a "release date" by technical professionals) within the App Store: While viewing an individual app, have the "Details" button selected, then scroll down to the bottom where you can select what is called "Version History" to see consecutive application versions of the particular app, version number with a version update date if that information has been posted.
Another discussion about App Store Missing Application Review Dates is taking place in this Apple Support Communities thread.