For version 1.1.1 and above, the version number is displayed at the footer of the application.
The version number is at the bottom, next to the powered by Jumptree.
If you do not see a version number, then go to the /App_Data/SqlScripts/ folder.
If you see the file UpgradeV1.0ToV1.1.sql, then you are using version 1.1.
NOTE: If you also see UpgradeV1.1ToV1.1.1.sql, then you're using version 1.1.1.
If you don't see that file, then you are using version 1.0.