Possible Duplicate:
How to display the current project version of my App to the user?
Is there a way to check the version number of my app? Is it supplied somewhere once the app is in the App Store?
I believe this is included in your info.plist file, and can be retrieved with code like this:
[NSString stringWithFormat:@"Version %@",[[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"]];