App Store should be located at this location:
/Applications/App Store
so, open the Applications folder, select the App Store application, and select "Get Info" under the "File" Command in the Finder. If it is not 1.0.2, or if the App Store app is located elsewhere, I suspect it is misinstalled. Try redownloading the 10.6.8 combo installer, apply it, then retry the App Store...