Was from squeak-dev, guess the [ANN] tag should be superflouous here!
Diff Tools are now available via the dev Universe and/or SqueakSource.
"The Diff Tools consist of a set of morphs designed to present differences
between versions of methods in a presentable manner. Generally two methods
are presented side-by-side with highlighting, by lines, additions, removals
Where there is a change, further highlighting is employed to identify the
changes within the affected lines."