"There are many reason for keeping backup copies of
apps that we download from the market:
* Re-installing an app that is no longer in the market
* Reverting to a previous version of an app that may have gone from
free status to paid status
"Note: Please keep in mind that there are some apps which can't
be backed up due to how the app author set the app up in the market
- many paid apps are set to "private" and thus cannot be backed up
without rooting the phone. However, the majority of apps are
capable of being backed up.
"I have found that many of the file manager apps in the market
include features for managing processes and backing up apps, but my
two favorites are:"