On June 1st, 2010 Twitter will drop usage of the basic authorization mechanism and only accept OAuth authentication. This means that all functions in twitter.lsp (accessible from the Tips&Tricks page) requiring authentication, will cease to function. Only the search function will still work.
Something new could be put together using (exec "curl ...") for HTTPS access. In a June 2007 post, Cormullion describes, how to do this:
http://newlisper.blogspot.com/2007_06_01_archive.html
For the HMAC-SHA1 encryption mechanism used in oAuth, the newLISP crypto.lsp standard module can be used. I don't have the time to take care of this myself and will shorten current twitter.lsp to just the search function as June 1st approaches.
For the OAuth specification see here: http://tools.ietf.org/html/rfc5849
Ah, I remember the days of Blogger...
That post is also at //http://unbalanced-parentheses.nfshost.com/postingtogooglebloggerusingnewlisp.
I haven't used it for a couple of years now, so it might not work anymore, who knows.