The Sitecore version appears on the shell Login page. Which is typcally at http://domain/sitecore/login/
It may also pay to check the DLL versions as the interface might be lying about the actual version.
From code try:
- Sitecore.Configuration.About.GetVersionNumber
- Sitecore.Configuration.About.VersionInformation
- ~/sitecore/shell/sitecore.version.xml
