Twisted can support a wide range of protocols be it HTTP, FTP, SMTP, POP3, IMAP4, DNS, IRC, MSN, OSCAR, XMPP/Jabber, telnet, SSH, SSL, NNTP, or one of the really obscure protocols like Finger, or ident, or one of the lower level protocol- compared to node.js which is primarly based on HTTP protocols. It is a little bit boring library of python compared to others but it also helps to prevent other boring problems.
The learning curve for Node.js is much easier than Twisted if you don't already have experience using either one. For the Node.js Code lesson course that just finished, many developers were able to create non-trivial applications in a few short days. Also, the python documentation for twisted is not very well written.