Can I integrate Orbeon in another application?

I'm mostly interested in being able to load Orbeon into another runtime, in another framework, and use it to generate XHTML output for a form. I have no need for any Orbeon server components. All I need to do is generate XHTML from XForms input. Said output should have all the required .js includes and such to make it work properly.

Can Orbeon do this?

To the initial question "can I integrate Orbeon in another application", the answer is of course yes. Orbeon Forms has a few ways of doing this, see in particular Using the Orbeon Forms XForms Engine with Java Applications.

To the implied question "can I do this without any of the Orbeon server components", the answer is no: Orbeon Forms requires a server component to run. As Alain mentions, in that case you could look at some pure client-side solution like XSLTForms.