I am looking for a solution to show a summary of revision history for all nodes in one place. The out of the box solution is to show a revision history for each node apart. I want to be able to track my content admins' changes in one place (I couldn't find a module that does what I want) Thanks!
If you don't mind to use Views module, you can configure any list of revisions. You also can add filter/sort logic, pager, configure access and much more useful things.
You always can export your solution with Views export or with Features module and reuse it on other Drupal sites.
More information about Views: http://nodeone.se/en/node/20
There are severel modules that extend revision, one of this is Revisioning.
Another way is create a view of revisions.