I found that presentations which were in my repl input history, weren't being recalled as presentations when I recalled previous history - they were coming back as text, and so would generally trigger a reader error when I tried the command.
I tracked this down to
(defun slime-repl-replace-input (string) (slime-repl-delete-current-input) (setq it string) (insert-and-inherit string))
If one uses insert, instead of insert-and-inherit then repl history works correctly for presentations, for me.
No idea why this is problematic. It looks like this function has been this way for a long time - perhaps a bug in the emacs I am using (OS X tiger, fink installed, I think).
Anyways, thought I'd post this in case anyone else was having the same problem, or had some insight as to why this is happening.
-Alan