MacOS – Mountain Lion: How to see the description of a software update after I’ve installed it

From Daring Fireball:

Panic on the Mac App Store

Cabel Sasser on what it’s like for existing Mac apps that are now in the App Store:

PS: If you’re a current customer, there’s no way to convert a previous purchase into a Mac App Store purchase — that requires a re-buy. But remember, what you have now will continue to work just fine.

UPDATE: The Mac App Store may show software bought from us previously as “Installed”, even though they’re two different licenses. You will not get Mac App Store auto-updates unless you purchase from the Mac App Store. To re-enable the “Purchase” button in the Mac App Store, just drag the app to the trash. Your preferences/sites will not be affected.

In other words, for apps that use the same bundle ID for the both the Mac App Store and non-App Store versions, the Mac App Store will not install updates to already-installed non-App Store versions, but it will recognize them as being already installed. If you want to get updates via the Mac App Store, you’ll have to re-buy the app through the App Store.

It appears that some updates have others as prerequisites, and will not show up as available until the others are installed. Thus, Software Update makes a list of all eligible updates, then runs. If a subsequent update was also pending that was not eligible to be downloaded because its prerequisite has not not yet been installed, that update would not make the list. The subsequent check, however, would see if any new updates had been unlocked by the updates installed.