This menu item is available if a document, text document or Text Block locked by the current user is selected. It will compare the [in development] revision with the [current] revision. It is called View my changes because the [current] revision was opened when you started editing the object and your changes are stored in the [in development] revision. Comparing the two will show what you have done.
Note
This menu item is not available for OpenOffice.org documents.