Hi All,
After installing SBCL 1.50 and the most recent CVS version of slime on a linux machine (Ubuntu 11.04), I needed to change slime.el in order for M-x slime to work within emacs.  I don't know why this was necessary, but I changed the slime-init-command function to include a :dont-close t argument to the swank:start-server call.
Here is my .emacs:
;;;; SLIME                                                                                                                                                                                                                                  
(add-to-list 'load-path "~/lib/cl/slime/")  ; your SLIME directory                                                                                                                                                                          
(setq inferior-lisp-program "sbcl") ; your Lisp system                                                                                                                                                                                      
(setq slime-net-coding-system 'utf-8-unix)
(require 'slime)
(slime-setup '(slime-repl slime-fancy))
I'm not sure if this is a bug or not, but perhaps you all should know.
Thanks,
Red