AppleScript to retrieve the version and build number of the frontmost/open app.

Open-App-Version.scpt

tell application "System Events"
	set activeApp to first application process whose frontmost is true
	set appName to name of activeApp
	set plistFile to (path of alias of file of activeApp & "Info.plist") as text
	tell property list file plistFile
		set appVersion to value of property list item "CFBundleShortVersionString"
		set appBuild to value of property list item "CFBundleVersion"
	end tell
end tell

set appInfo to appName & " " & appVersion & " (" & appBuild & ")"