Somewhere along the way — I think it’s related to an Apple Mountain Lion update — hitting “Show in Finder” after you downloaded a file in using the Google Chrome browser stopped working. Opening files from this tab may have been affected too (I tend not to use that functionality that often).
This is a pain. So much easier to find downloaded files by clicking right within Chrome than opening a new Finder window and navigating to downloads, which is likely over-populated with files with unfamiliar names, and then you sorting by recent to determine which file you downloaded.
In any case, here’s a fix:
Open the Terminal App and type/cut & paste the following:
$ sudo killall -KILL appleeventsd
Hit return, enter your password, and you should be all set.