Those service types are just options when you create "Accounts" on the system. I believe the first time you go into something like the "Chat" application it will prompt you to set up an intial account of some type (gtalk, jabber, sip). (If not you can always create/edit/delete them via the "Accounts" section in the "Control Panel").

Once you have an account (or several) defined, you can enable it, set your presence, and change your preferences on the fly via the icon in the system bar. Really I think it's pretty well integrated.