jQuery walkthrough plugin

Question

Is there a plugin that can help create javascript app/site walkthroughs?

If not, (I can't find any via google, though I could've sworn I knew of at least one), is it a good idea (for a moderately complex app)? How does it compare to screencasts? What are some best practice if you were to do one? And in general terms, what are some ideas for how to go about it.

Thanks in advance.

Edit: As an example, something like this I just found.

Answer 1

2009 Solutions were sparse.

2012 Solution is Joyride.