Here http://blog.couchone.com/post/1027100082/whats-new-in-couchdb-1-0-part-4-securityn-stuff it says that jquery.couch.js is the standard JavaScript API that ships with CouchDB.
But how do i get the jquery.couch.js file from couchdb so I could use it's functions ($.couch.signup, $.couch.login etc) in my Sproutcore application or another frontend application?
Futon uses this API itself, so you can see where it includes it, as well as other dependencies it may have, depending on what you'll be doing. Since the CouchDB server can serve up HTTP requests, you can also pull in the dependencies like Futon does.
<script type="text/javascript" src="http://localhost:5984/_utils/script/jquery.couch.js"></script>
Obviously you'll change the hostname to match your couchapp's hostname.