Currently Being ModeratedOct 25, 2012 5:46 AM (in response to Computable User)
search your Mac for Keynote, there are a number of small files located in different places. If you delete these and select custom install for Keynote, you will have a fresh install of Keynote.
Currently Being ModeratedOct 26, 2012 3:45 PM (in response to Computable User)
There is no "Keynote 2012". The Keynote standalone app that is now available in the Mac App Store is the same as the one that came on the iWork '09 install disc, it's just been (very slightly) updated for Mountain Lion and iCloud compatibility.
If you have been doing your software updates, your existing (that is, before you deleted it) version of Keynote should have received the incremental updates over the years. You could confirm this by looking at the actual version number of Keynote in the MAS (v. 5.2) and the one on your hard drive (select it in the Applications/iWork/ folder and do a Get Info by pressing Command-I).
As for when we might ever see a Keynote '12... or '13... or '14... frankly, I've stopped holding my breath....