Question: I'm unfamiliar with the new oauth system. I wanted to crawl the status updates of my friends, and their friends' (if permissions allow) with my specified account credentials using the python-twitter api. 

With the new oauth authentication, does it means that I have to first register an application with twitter before I can use api?

Answer: 
Yes, thats right. You need to register it and connect "grant access" it with your twitter id, if you want, for example, post something on your twitter wall. Also see "connections" in your twitter id.
For use api you must register your aplication or use GET methods to post into twi through web interface.