The web help is great place to start. Here's the first page, just work your way down.
http://help.arcgis.com/en/arcgisserver/10.0/help/arcgis_server_dotnet_help/index.html#/What_is_a_ver...
If you have access to an ArcSDE geodatabase and the ability to view the system tables (i.e. Sql Server Mgmt. Studio, Sql Developer) you can create some data, create versions, edit, reconcile, post and then look at what the tables are doing. It's a good way to understand the back-end processes which can translate into better version management.
Also, check out the geodatabase blog...
http://blogs.esri.com/Dev/blogs/geodatabase/archive/tags/Versioning/default.aspx