On PageNameChangeRequests you can find the following explanation:

Anyone can set his own level to experienced deshi in the user preferences and then add spaces, hyphens, commas or any punctuation mark which is accepted by the engine (i.e. rename "LibertyTacticalSense" to "Liberty (tactical sense)".

Changes which affect the JoinCapitalizedWords spelling, however, can only be done by librarians, an access level given by the admins.