OK, it looks like that JRails is better for dealing with Rails2, but not for Rails3!
So there is only one question left: If a install the "jquery-rails" gem like you mentioned, are the prototype helpers still working?
Right now I am using your code in html tags and it is working like a charm, like this:
<head> <script src="http://code.jquery.com/jquery-latest.js"></script> <script> "Your code snippets here!" </script> </head>
But that means I have that on every view!