<p>In a web application I am developing, I wish to implement wiki-style edits (where each and every edit is saved, can be compared, and users can rollback edits easily).</p>

<p>What is a good way of implementing this without re-inventing the wheel too much?</p>

<p>Thank you in advance.</p>

I believe you're really seeking a
Content Management System
(CMS), of which a Wiki is a specialization (IMHO).
Googling '
CMS Open Source
' brings as its top hit:
Open Source CMS
, try before you install
Joomla
Drupal
Wordpress
And a
lot
of other information.
Commercially, I really like Atlassian's
Confluence
.  Wiki like markup, editing history, easily attach documents and now supporting editing in Word, Excel & Powerpoint.